Mazocarpon Oedipternum, Sp. Nov

STATE OF ILLINOIS DWIGHT H. GREEN, Govornor DEPARTMENT OF REGISTRATION AND EDUCATION FRANK G. THOMPSON, Director

DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief URBANA

REPORT OF INVESTIGATIONS-NO. 75

Contributions to Pennsylvanian Paleobotany

MAZOCARPON OEDIPTERNUM, SP. NOV.

AND SIGILLARIAN RELATIONSHIPS

JAMES M. SCHOPF

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS

URBANA, ILLINOIS 1941 STATE OF ILLINOIS HON. DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. FRANK G. THOMPSON, Director

BOARD OF NATURAL RESOURCES AND CONSERVATION HON. FRAKK G. THOMPSON, Chairman

EDSON S. BASTIN, Ph.D., Geology WILLIAM TRELEASE, D.Sc., LL.D., Biology WILLIAM A. NOYES, Ph.D., LL.D., Chem.D., D.Sc., EZRA JACOB KRAUS, Ph.D., DSC., Forestry Chemistry ARTHUR CUTTS WILLARD, D.Engr., LL.D., LOUIS R. HOWSOX, C.E., Engineering President of the University of Illinois

STATE GEOLOGICAL SURVEY DIVISION LTRBANA

M. M. LEIGHTON, Ph.D., Chief ENID TOWNLEY, M.S., Assistant to the Chief JANE TITCOMB, M.A., Geological Assistant

GEOLOGICAL RESOURCES GEOCHEMISTRY

Coal FRANK H. REED, Ph.D., Chief Chemist G. H. CADY, Ph.D., Senior Geologist and Head ROBERTA M. LANGENSTEIN, B.S., Chemical Assistant L. C. McCABE, Ph.D., Geologist (on leave) R. J. HELFINSTINE, M.S., -4ssoc. Mech. Eng. Coal JAMES M. SCHOPF, Ph.D., Asst. Geologist G. R. YOHE, Ph.D., Assoc. Chemist J. NORRIAN PAYNE. P11.D.. Asst. Geologist MYRON H. WILT, B.S., Research Assistant CHARLES C. BOLEY, M.S., Asst. Mining Eng. BRYAN PARKS, M.S., Asst. Geologist Irzdz~strial Minerals J. S. MACHIN, Ph.D., Chemist and Head Indzistrial Minerals DELBERT L. HAKNA, MS., Research Assistant J. E. LAMAR, B.S., Geologist and Head H. B. WILLMAN. Ph.D.. Assoc. Geoloeist DOUGLAS F. STEVENS,' M.E., ~esearchAssociate Fluorspur ROBERT M. GROGAN, I'h.D., Asst. Geologist G. C. FINGER, Ph.D., Assoc. Chemist ROBERT R. REYNOLDS, B.S., Research ~siistant EVERETT W. MAYNERT, B.S., Research Assistant Oil and Gas X-ray and Spectrography A. H. BELL, Ph.D., Geologist and Head W. F. BRADLEY, Ph.D., Assoc. Chemist G. V. COHEE, Ph.D., Asst. Geologist FREDERICK SOUIRES. B.S.. Assoc. Petr. Ena. Analytical CHARLES W. CARTER, Ph.D., Asst. ~eologist 0. W. REES, Ph.D.. Chemist and Head WlLTAAM H. EASTON, Ph.D., Asst. Geologist L. D. McVICICER, B.S., Asst. Chemist PAUL G. LUCKHARDT, M.S., Research Assistant P. W. HENLINE, M.S., Asst. Chemical Engineer WAYNE F. RIEENTS, Research Sssistant ARNOLD J. VERAGUTN, MS., Asst. Chemist WILLIAM F. WAGNER, MS., Asst. Chemist Areal and Elzgineerirtg Geology K. F. BURSACK, B.A., Research Assistant GEORGE E. EKBlAW, Ph.D., Geolo~istand Head RICHARD F. FISHER, Asst. Geologist MINERAL ECONOMICS

Sz~bszirfaceGeology W. H. VOSKUIL, Ph.D., Mineral Economist L. E. WORKMAN, RI.S., Geologist and Head GRACE N. OLIVER, A.B., Assistant in Mineral Economics TRACY GILLETTE, Ph.D., Asst. Geologist ARNOLD C. MASON, B.S., Asst. Geologist KEENETH O. EMERY, Ph.D., Asst. Geologist EDUCATIONAL EXTENSION MERT'YN B. BUHLE, MS., Asst. Geologist FRANK E. TIPPIE, B.S., Asst. Geologist DON L. CARROLL, B.S., Assoc. Geologist Stratigraphy and Paleontology PUBLICATIONS AND RECORDS J. MARVTN FELLER, Ph.D., Geologist and Head CHALMER L. COOPER, MS., Assoc. Geologist GEORGE E. EKBLAW, I'h.D., Geologic Editor CHALMER L. COOPER, MS., Geologic Editor Petrography DOROTHY E. ROSE, B.S., Technical Editor RALPH E. GRIM, Ph.D., Petrographer KATHRYN K. DEDMAN, M.A., Asst. Technical Editor RICHARDS A. ROWLAND, Ph.D.. Asst. Petrographer ALMA R. SWEENy. A.B.. Technical Files Clerk PORTIA ALLY N SMITH,' Asst. Technical Files Clerk Physics RUTH E. ROTH, B.S., Asst. Technical Files Clerk R: J. PIERSOE, Ph.D., Physicist MEREDITH M. CALKINS, Geologic Draftsman DONALD 0. HOLLAND, M.S., Asst. Physicist LESLIE D. VAUGHAN, Asst. Photographer PAUL F. ELARDE, B.S., Asst. Physicist DOLORES THOMAS SIMS, B.A., Geologic Clerk

Consultants: Ceramics, CULLEN W. PARMELEE, M.S.. D.Sc., and RALPH K. HURSH, B.S., University of Illinois; Pleistocene Intiertebrate Paleontology, FRANK COLLINS BAKER, B.S., Thiversity of Illinois; fifechanicnl Engineering, SEICHI KOXZO, MS., U11i.i-ersily of Illinois. Topographic Mapping in Cooperation with the United States Geological Survey. This Report is a Contribution of the Coal Division, Geological Resources Section. August 1, 1911 o.v@lg+&2 -F->7c-- CONTENTS

Preface ...... 5 Iiitroduction ...... 7 Acknowledgments ...... 8 Age relations of coal-balls containing Muxocarpon ...... 8 Illinois coal-ball horizons ...... -10 European coal-ball horizons ...... 11 Discussion ...... 13 Description of new material ...... -14 iMaxocarpon Benson. ex Scott, 1909 ...... -14 Muxocarpon oeclipternumz SP. nov ...... 14 Forma megaZopho~unz,forma nov ...... -15 Forma microphorum. forma nov ...... -15 Morpho.logic features ...... -16 Comparison of 111 . oedipternum with other species of Maxocarpon...... 22 Maxocarpon pettycurense Benson ...... -22 Muxocurpon ca'shii ...... 22 Muxocarpon shorense ...... -22 Relation of Maxocurpon to affiliated groups of plants ...... 25 Peduncular steles of Xigillaria. and Mazocarpon ...... -27 Relation of Maxocarpoin and Xigillariostrobus ...... -28 Specific relationships ...... 3z Relation of Paleozoic lycopod groups ...... -31: Free-sporing character of Maxocarp.o.n...... -34 Maxocarpon and Lepidocarpon ...... 35 iMaxocnrpon and Xpencerites ...... -35 Conclusion ...... -36 References ...... -3'7

PREFACE

Applied research on coal has revealed the fact that there is a dearth of fundamental information regarding the nature of the original plant material from which the coal was derived. It is therefore necessary to carry forward a parallel program of fundamental studies whose results should give new concepts that will make applied research even more productive. The present paper represents an important contribution to the lcnowledge of spores and to the relationship betmeen certain types of spores and certain kinds of trees that contributed to the mass of vegetation from which {the coal beds were derived. Among the constituents of coal there are certain plant tissues that endure better lthan others the changes, severe compaction, and other solidification effects, of the transformation of plant material into bitu- minous coal. Even in the compressed solid material of the coal in Illinois, such tissues or organs can be found so little altered from their original appearance that they can be readily identified. Also, because of their relatively great re,sistance to oxidation by chemical reagents, it is possible to isolaite them completely from the rest of the coal so that they can be examined and photographed. The most interesting of these forms are the plant spores, which may make up a large percentage of the mass of a coal and hence definitely affect the property of such a coal, and which are also valuable as a record of the forms of vegetation that contributed to the coal bed. The present paper is concerned mainly with the investigation of certain parts of the kinds of plants of which the coal beds are composed. The spores vary considerably in their outer form and appearance because of differences in shape and differences jn the kind of ornamentation. Shape and ornamentation have been ~~sedby paleobotanists as a basis of elaborate and complicated form-classification of spores. This is largely because of the uncertainty as t40the identity of the spores in terms of the parent tree. For the purpose of relating spore varieties to definite plants, it is fortunate that Illinois coal beds have yielded several important deposits of fossilized peat in the form of coal-balls. These coal-balls are petrified masses of peat material which is preserved essentially in the condition in which it existed in the peat deposit before the overlying strata were deposited. Calcite was deposited in the open cell spaces and in all other open spaces in the peat or in spaces filled only by liquids, thereby fixing the tissues in their relatively unconsolidated form. Such fossilized peat contains all the kinds of plant forms that compose the surrounding normal coal bed. Spores are not uncommon components of the coal-balls, but ~vliatis more important to the paleobotanist is the fact that spores are found associated with the organs from which they were produced and the cones containing such organs. Once certain cones and certain spores arc. definitely linked together, it becomes much easier to identify the spores in terms of the plants from which they were derived. Thus a step in the process of classifying spores in a natural way is, accomplished. Extended iiivestigations of this lrind will be necessary before a satisfactory nnclerstancling of the relationsllips of spores found in Illinois coals will be attained. Since it is only a matter of chance that cones containing spores will be contained in any coal-ball, advantage should be taken of the opportunity to study new varieties of cones whene~ersuch discoveries, are made in order that the classification of the spores may proceed as vapidly as possible. All of this work should lead to a taxonomic classification of the plants which make up the coal beds-a classification which may ultimate- ly play as important a part scientifically and industrially as the classification of our modern flora has played. -GILBERT H. CADY, Selzior Geologist arid Head of the Coal Divisio?~. Contributions to Pennsylvanian Paleobotany

I13AZOCARPON OEDIPTERNUM, SP. ~ov.

AND SIGILLARIAN RELATIONSHIPS

BY JAMESM. SCHOPF

IIE PURPOSE of this paper is to de- ample to indicate that botanical affinity Tscribe a new species of plant which between species based on spores alone is illustrated by a remarlcable series of can be established with reasonable pre- cones from tlie Calhoun (Xichlancl cision. Couiltp) coal-ball horizon in Illinois. Recognition of the botanical affinity nIaxocarpo?~ oeclipter~zunz, although of the Apha?zoxonnti greatly increases scientifically interesting in itself, is sig- the -~~sefulnessof these spores in coal ~lificant chiefly because it helps to studies and in stratigraphic paleobotany. clarify the relationship between groups Well-preserved megaspores can gener- of Carboniferous plants that have sigil- ally be recovered even from thin coal Iarian alliance. beds, carbonaceo~~sshales, aiid carbon- The close relationship of Muxocarpon aceous sandstone laminae which do not and Xigilla&, previously suggested by provide other. identifiable fossils. The 13enson (1918) and Haghe (l926), re- possibility of identifying spores in terms ceives additional support in the evidence having definite botanical significance presented in this report. Xiy illuriostro- increases their nsef~nlness i11 strati- bus and Maxocccrpon are shown Lo be graphic correlation ancl in plant popu- closely allied, and one of the most im- lation studies. In the latter capacity portant results of this study is recogni- they may aid in explaining differences tion of the relationship of spores classi- in constitution among the various types fied under. the section Aphunoxonuti of of coal. Triletes and the sigillarian alliance. Altliough the affinity of the aphano- The coiiclusion that the Aphanoxmzati zonate megaspores is probably of great- represent a natural closely allied group est immediate interest, the related cones of plants was reached in an earlier st~ndp provide a good deal of additional paleo- (Schopf, 1938, b, pp. 23-24). At that time botanical information. Heretofore the it was not known what particular group anatomy of sigillarian fr~xtifications, of lycopods was represented nor how and particularly of the microsporangi- trustwortl~yspore resemblances were for ate struct~lres, has been inadequately evaluating plant relationship,^,. Spores known. Microsporangiate cones are now of tlie sigillarians (the Ap7zanoxonati) described from abundant material. Well- r:ow appear to be identifiable thro~ngh- preserved female gainetophytes can also o~~ttlie Pennsylvanian system. By an- be described more completely tliaii was alogy, and in the absence of conflicting possible before. Thus considerable new evidence, resemblances among other information is available to illustrate the kinds of spores assume a greater im- ~eproductivephases of a sigillarian life portance since m7e have the present es- cycle. The present paper by no means ex- reading of the manuscript and his con- hausts the possibilities of botanical structive comments. Mr. Revilo Oliver study on the Calho~m collections of of the University of Illinois Classics De- Maxocarpon. It seems desirable, how- partment, has aided in the selection of ever, to publish the data which are now the new scientific names. Professor L. available so that they may be of use. M. Cline of Iowa State College, Ames, A complete study of this excellent ma- has kindly provided correlations for sev- terial ill require much more time. eral coal-ball occurrences in Iowa. The assistance of Professor H. R. Wanless and Dr. J. M. Weller in stratigraphic ACKNOWLEDGMENTS interpretation and the cooperation of other members of the Survey staE is The author wishes to express his ap- gratefully acknowledged. Many of the preciation to Dr. G. H. Caciy for en- sections used in this study of Muxocarpon couragement during the progress of this have been prepared by Mr. E. Allen ~orli,and particularly for his careful Platt.

AGE RELATIONS OF COAL-BALL PETRIFACTIONS WITH R,EFERENCE TO THE GENUS MAZOCARPON

The occurrence of Jfaxocarpon in the tive correlation may be arrived at which upper McLeansboro Calhoun coal-ball enables LIS to place the Calhoun material horizon was first repo~tedby Graham in its approximate position in the time in 1935. A p~~blishedlist (Fisher-No6, sequence. This is summarized on the 1939) of coal-ball plants from the Cal- chart given in text figure 1. Further houn (Richland County) locality refers information is given in the many papers to this form as Maxocarpo?z s7zoremse published in the Proceedings of the 1927 Eenson, although H.shorense had been and 1935 Heerlen Congresses on Car- reported previously only from m~lcli bonif erous strati graph^.^ Miss Dix7s older lower Westphalian strata in west- (1937) correlation of English Upper ern Europe, and Graham's mention of Carboniferous with the standard West- N. shorense in this connection was only phalian section has been helpful. Hir- comparative. It now appears that the mer (1940) has recently s~~mmarizedin Calhoun iVaxocarpm, i. e., M. oedipter- detail the stratigraphic extent of Upper ?zunz, is distinct, from Maxocarpon shor- Carboniferous floras in northwestern ense. The improbability of the species continental E~~rope,and Jongmans being the same is evident from consid- (1940) has given a useful summai-y of eration of the difference in age between the British Coal Measures stratigraphy. well known European and American W anless ' (1939) recent correlation of coal-ball horizons. the Appalachian and Eastern Interior The horizon at which any fossil speci- basins is the most satisfactory treatment men is found is important in considera- available dealing with this difficult s~xb- tions of its relationship and phylog- ject. More recently, stratigraphic classi- eny. Hence it is essential that the ge- fication of the Pennsylvanian system in ological age relations be critically con- Illinois has been revised (Weller, 1941) . The Caseyville, Tradewater,' Carbon- sidered before conclusions are drawh as dale, and McLeansboro beds are now to the biological relationship of species recognized as groups instead of forma- of Mnxocarpo?a and the species of other lExact titles cited under "Heerlen" in the list of genera closely related to it. references, pp. 38-40 of this report. Correlation of Carboniferous beds in 2Use of the term "Pottsvillc" ns applied to beds America and Europe, or even between of Casevville and Tradewater age has been dis- continued by the Illinois Geological Survey. The different coal fields in either continent, Potts~illebeds are generally accepted as equivalent to the Pocahontas, New River, Icanawha still offers many problems, but a tenta- succession in the Appalachian region. AGE RELATIONS OF COAL-BALLS

EUROPE W

Autun (France 1

$J 5 Grand ?

- . $30 I x --- >[>Garnett Holzer Kongkm 0 2 (Kansas) ( Saar. etc. ) <*P rker 7 lndiana) 5 ~anvllle AHerrin gi~arrisburg Ll z 2 2 5-Tebo coal zg~azonsh. Xr>(HenryCo. - Palzo ss. z*~ock Island ,, Missouri) k 3 9 -t-

-1 PBat tery t; Rock sh. 2 Hindostan %(Orange Co. - Ind~ana)

t'n 2 E s=+Little U U, Limestone 2 2 Coal wu Y-Z (Nort hurnberland) m 6

% Mazocarpon occurrence

La DEVONIAN OLD RED FIG.1-Chart showing correlation of Carboniferous beds in America and Euro~e. tions by the Illinois Geological S~~rvey. most other coal-balls in that they are Details of the mid-continent section silicified, b~~tsince they are entirely in- have been discussed by Moore (1936). cluded within a 6- to 10-inch coal bed Most trustworthy intercontinental cor- and sliom tlie characteristic type of relations apparently can be made be- plant tissue preservation there seems to tween the middle Pottsville New Rirer be no reason m7hy they should not be beds and the Westplialian A. For ex- called " coal-balls ". The occurrence is ample, Bertrand (1933, 1935), Moore unusual because silicified plant material (1937, p. 671), aiid D. White (posthum- is not ordinarily found in Illinois coal OLIS ~mp~~blishedmanuscript recently beds. David White (1925, p. 10) at- completed for publication by Charles B. tributes the " segregative precipitation Eead) have all suggested that the Na- of colloidal silica" to rapid invasions murian-Westphalian boundary is at of saline or brackish water at the time least approxiniately correlative with the of, or very soon after, deposition of the Pocaliontas-New River bo~mdaryin the plant material. Unfortunately, he did American Pottsville. The Carboniferous- not cite instances which he undo~~bteclly Permian boundary seems fairly well es- had in mind, and we have no way of tablished in some areas but is still con- knowing whether the Illinois silicified troversial in others. T~LISthe relative coal-balls correspond exactly with his age of the three species of Haxocarpon interpretation or not. that are now known can be established The nest lower coal-ball occurrence approximately, and this is the first step is the Calhoun (Richland Co~~nty)coal in understanding the phylogeny and in horizon from which the lien7 species de- adding to the stratigraphic usef~~lness scribed in this paper, Maxocarpo~toedip- of this group of plants. icr~zwn, was obtained. The Calhoun Mnxoccrrpon is generally definable only horizon is in the upper part of the Mc- on the basis of petrifactions, and these Leansboro group of Illinois. Recent are most coniinonly found in Carbon- studies have indicated that the Callioun iferous rocks as fossils in coal-balls. horizon is stratigraphically higher than Further investigation of coal-ball fossils it was previously considered by Newton will doubt1 ess supplement the somewhat and Weller (1937). Its relative posi- scant information now available as to tion is somewhat uncertain although it the occurrence of Maxocarpon and will is linown to be considerably higher than also provide other fossils of geological the LaSalle 1imestone.Vhe limestone and botanical importance. Because of that overlies the Calho~mcoal bed, and this, and the fact that the relative strati- is continuous in a few places with the graphic positions 01 various coal-ball pockets of coal-ball concretions in the ho~izonshave comnionly been disregard- coal bed itself, has been called the Cal- ed, most of the significaiit coal-ball ho~lnlimestone by Grogan and Lamar horizons of America and E~~ropehave (1940, p. 42). About 800 feet below it also been indicated on the chart (fig, 1) is the Herrin (No. 6) coal which marlre in their approximate relative positions. the top of the Carbondale group in Illi- A few other horizons, significant in cor- nois. Feliciano (1924, p. 232) has listed relation or as a source of important coal-balls from the Calhoun locality as plant fossils, also are indicated. if they were from tlie I3errin (No. 6 j coal, but the I3errin coal is not mined ILLINOIS COAL-BALL I3ORIZOWS and does not crop o~~tin this part of the State. Niss Reed (1939, pp. 770-771) has Seven coal-ball horizons are now rec- stated that the Calhoun coal-balls "are ognized in the Illinois basin, and others of the same geologic age as those from mill probably be discovered. Two, the EIarrisburg, but tlie Harrisburg coal- Shumway and the Parlrer, are here re- " ported for the first time. balls are from the second coal below the Hemin (No. 6) coal, and are thus from Coal-balls from the Sh~~mwaycoal, at the top of the Illinois section, contain the Carbondale group. chiefly fern material. They differ from 3Weller, J. M., personal communication. AGE RELS1'IOhTX OF COA4L-BALLS 11

Coal-balls mere obtained at abo~~tthe Indiana) is in the Minshall coal which horizon of the coal in Posey is equivalent to the Rock Island coal County, Indiana, in 1938. This occur- according to Wanless (1939). Coal-balls rence was first discovered by John Les- have been recorded from central Iowa ter, formerly of tlie Stratigraphy and west of Des 3'Ioines by Darrah (1939). Paleontology Division of the Illinois The coal is reached by shaft mines, and Geological Survey. The position of this its position is less definitely established coal in the stratigraphic sequence has than that of the other horizons men- been placed by J. If. Weller a short tioned, but according. to Dr.. L. If. Cline distance above the horizon of the Lons- the coal is probably-the same as Lngn's dale limestone. Collections have been (1927) Lucas Co~tnty"Lower Coal)', made but are still unstudied, although which may correspond in age to the characteristic fossils of Psuronizcs and Rock Islancl bed of Illinois. Darrah men- ~Wz~cloxylonhave been observed. tions that Jfuxocarpo.rz occurs in these Coal-balls from the Danville (No. 7) coal-balls but the results of his study are coal (very near the base of the Mc- not yet available. Coal-balls considered Leansboro group) have been reported to bc from the same horizon have been by Feliciano (1924) and others. Coal- obtained near Indianola, Ion-a, by EIos- Idls reported from near New Castle, kins and Cross (1941). Other Iowa coal- Texas, cannot be definitely correlated ball material is being studied by L. R. with the Dandle (30. 7) coal, ax the Wilson and his students at Coe College. chart p~~blishedby Feliciano suggests, Feliciano also listed coal-balls col- and this record at present seems in- lected by No6 from Bloomfield, Davis conclusive because ns plant material has County, Iowa. The only coal-balls 17sown yet been reported. in this vicinity are from the Lower Sea- Numei-om coal-balls have been obtain- liorne coal, according to recent studies ed from the Herrin (No. 6) coal at the by Cline. This coal is above the Rock top of the Carbondale group, first re- Island horizon, in the upper part of the ported at Nashville, Illinois, by Cady Tradewater group. (1936). Recently other occurrences have - also been ciiscovered in the Herrin coal. EUROPEAN COAL-BALL The Harrisb~xrg(No. 5) coal is the sec- HORIZONS ond coal bed encountered below the Eistologic preservations of plant de- fIerrin coal in the vicinity of Harris- bris of lower Permian age has been re- burg. The first American coal-ball to be ported from western Europe in many recognized as such mas obtained from studies. Similar material of Stephanian tlie Harrisb~~rgcoal by Dr. G. H. Cady age in central France has also been the and transmitted to Professo~A. C. No6 subject of m~~chinvestigation. Most of who later collected more of them. Sev- these petrifactions are silicified. Al- eral studies of coal-ball plants from this though the plants are comparable in collection have been published by J. H. preservation to those from coal-balls, Hoskins, H. V. 'Krick, and F. D. Reed. they apparently have no relationship to The lowest horizon in this basin to beds of coal, and consequently the petri- have provided coal-balls is the Rock factions m~xsthave been formed differ- Island (No. 1) coal in the upper part ently. They are mentioned because they of the Tradewater group. At least five seem to provide the most abundant com- thin but generally persistent coal beds parable paleobotanical material that is occur above it and below the base of younger than that in Illinois coal-balls, the Carbondale gro~xp.VheSilverwood and some of the plants found here may (Silver Island) coal-ball occurrence re- have an ancestral relationship to some ported by Feliciano (Fo~mtainCounty, found in Stephanian and lower Permian deposits. *The Palzo sandstone member is now considered to represent the basal bed of the Carbondale In 1845 Corda (1867) described in group (Cady 1941). Wanless (1939) used the Sebree=Isabel? sandstone as a boundary but the the "Protogaea" a few plants from the precise equivalence of those beds is in' question coal mines near Radnitz in central Bo- and the Isabel, at least, may lie somewhat higher than the Palzo. hemia which were histologically preserved and apparently similar to those and in Limberg (Holland) and in the in coal-balls. Kubart (1911) later re- Ruhr it is the ' ' Finef rau-Nebenbank '. examined some of Corda7s original ma- Because of its importance as a source terial but was ~xnableto obtain any new of coal-ball plant fossils this horizon specimens or ascertain the original may be termed the Great Coal-ball hor- source. Nemejc (1937, p. 687) has char- izon. It seems that for many years coal- acterized tlie floras of Carboniferous ball fossils found in this co~~ntryand strata of the region and concludes that elsewhere will require comparison with they range in age from tlie transition at forms previously described from this the top of Westphalian B into the Per- Great Coal-ball horizon, as it is the only mian b~xtthat the lower Stephanian is one whose flora is adequately known. not present. Presumably Corda7s coal- Stopes and Watson (1909) showed balls came from somewliere in this se- that the seam which contains coal-balls quence, probably (judging from the fos- long lznown from localities near Staly- sils) from the upper Westplialian. Little bridge and Ho~xghHill ~~7aslower than is known about, fossil plants in coal- the Ganister (Great Coal-ball) horizon. balls reported by LeClerq (1925) from Miss Benson also obtained Mctxocarpon the Petit Baisson coal (Aegir) horizon s7zorensc from these localities. Coal-balls in Belginm. Fossil plants in coal-balls were also reported by Stopes and Wat- fron the Katharina coal in Limberg in son from above the level of the Great Holland and the Aachen district in Ger- Coal-ball horizon in central England in many are well known, chiefly thro~~gh the "Great Harwood" seam, and in recent investigations by Hirmer. Lists the "Arley mine7' coal at the top of the of species present and other references ' 'Lower Coal Aileasures (Upper part are included in his papers cited for 1928 of the Lanarliians) . Floras from these aid 1938. This bed is generally accept- coal-balls have not been described to Ihe ed by Ellropean geologists as the bound- author's knowledge. ary between Westphalian A and West- Kubart (1908, 1914) described a few phalian B. Coal-balls are reported by very interesting pteridospermic species Zalessky (1910) from the Donetz basin from coal-balls in the Kolrsfloz in Lower in R~~ssia,the most important of which Silesia whose occLxrrence had been cle-- seem to be slightly older than the Kath- scribed by Stur in 1885. The strati- arina horizon and therefore in the West- graphic position is apparently well de- phalian A, but no very thoro~xghstudies fined, as this seam is the highest in the are known to have been made. Rand group, with marine beck above it, The most important of all European and the Poclihammerfloz, lowest coal of coal-ball horizons occurs in the lower the Sattelfloz group, is superjacent at a part of the Westphalian A. One per- short interval. The bo~mdarybetween sistent coal bed, which may be traced the Rand and the Sattelflijz groups re- from Westphalia into Belgium and is cently has been more precisely corre- recognized in central England by the lated with standard sections by Czar- presence of an overlying characteristic nocki, Bode, and others (cf. C. R. 2nd "marine band," has provided the ma- Heerlen Congress). jority of species of coal-ball plants now Coal-ball plants were reported by Ab- known. Among them is Naxocarpoin salom in 1929 from the Little Lime- shorense Benson. Important work was stone coal of the Lower Limestone group done on coal-ball fossils from this bed in the Carbonifero~xs Limestone series by English botanists particularly. In of Northumberland. T~LISfar the oc- Rngland the coal seam is Bnown as the currence is chiefly significant because a "IIalifa~~~or "Hard Bed7 coal, as the few species seemed to be present which ' 'B~xllion", " Mountain mine etc. In had previously been identified from the Idancashire, where it splits into two Upper Carboniferous Great Coal-ball beds, the upper bed is often called the horizon. If they are correctly identified "Upper Foot Seam" and the lower one (Crookall, 1939, does not accept the the "Ganister7 '. In Belgium the cor- determinations w i t h o LI t reservation) relative seam is t,he " ~onxharmont' these species transgress the important AGE RELATIONS OF COAL-BALLS 13

"floral break" first recognized by Kid- chian and mid-Continent areas. Tenta- st on in the English Carbonif ero~~s. tive correlations by Moore (1936, pp. One other important source of fossil 71, 144) suggest that the Missouri-Virgil plant material comparable to that in boundary is about eq~~ivalentto the age coal-balls is in the Calcifero~~sSand- of uppermost McLeansboro beds of 11- stone series of southern Scotlanci. The linois and is somewhere near the Cone- Pettycur limestone on the Firth of maugh-Monongahela boundary of the Forth in Fifesliire is most notable, par- Appalachian trough. Weller (personal ticularly since a third species of Maxo- comm~mication)has recently considered carpol$, M. pettycureme, comes from this that the McLeansboro beds may range locality. The age equivalence of this somewhat higher than this. limestone (a brecciated travertine ac- Thus the disparity between time of cording to Gordon, 1909) is apparently deposition of the two coal-ball horizons not precisely definable because it occurs in q~xestionis eq~~alto the greater part in a thick sequence of pyroclastic rocla of the Illinois Pennsylvanian section, and beds that lack suitable zonal fossils. including equivalents of much of Cone- Allen (1924) has given a rather detail- maugh, all of the Allegheny and Kan- ed section taken around the coast on awha, and a considerable part of the the iiortli shore of tlie Firth of Forth New River time intervals. The tendency TT-liichm~~st incl~tde tlie Pettycur lime- in the past has been to place the Illinois stone, although the bed is not identified il'lcLeansboro becis higher in relation to as such. Apparently its position is the European section than is indicated somev7here within the upper Oil Shale on the chart (fig. I), therefore it ap- group. Generally spealiing, the Calci- pears that the present estimate of the f erous Sandstone may correlate with lime interval is a conservative one, and beds of Lower and in part Middle Mix- the age discrepancy between these two sissippian age in America, which include coal-ball horizons may actually be Ihe Pocono-Price of continental facies greater. iVuxocarpon pettycurense from in the eastern Appalachians and marine the Pettyc~l-. limestone is, of course, beds in the Illinois basin. m~~cholder than either of the Upper DISCUSSION Carboniferous species. The Pennsylvanian of Illinois has The genus Maxocarpofi appears there- been correlated with that of the Ap- for to have a proved range extending palachian trough by Wanless (1939) fairly well through the Carboniferous. and others. As mentionetl previously The Calhoun occurrence is by far the there is some agreement of opinion con- yo~mgest. The infreq~~encyof reports cerning correlation of tlie New River of Maxocarpo.iz probably has been due to he& (middle Pottsville) with the West- lack of attention given to material from phalian A. Thus it is possible to arrive vhich it might be identified. That this at an estimate of the time interval is the case is supported by evidence separating the Calhoun horizon (con- derived from other closely related taining Muxocarpom oedip-ternzim) and groups of plants, discussed later, which the Great Coal-ball horizon from which are well lcnown from intervening hori- 1Naxocarpo~a shorense was described. zons. The continuity of Maxocarpon Since the latter horizon is not far above througho~~tthe Upper Carboniferous is the base of the Westphalian A, its important in that it shows more de- equivalent would be in the lower part cisively than mas possible heretofore of the New River group in West Vir- that the sigillarians are a discrete group ginia. According to Wanless (1939 ; al- of plants, distinct from other groups of so oral communication) this wo~~ldcor- arboreo~wlycopods, such as Lepidodew respond, in Illinois, to some horizon dron, Lepidoplzloios etc. that are also probably below the Battery Rock coal present in the same series of beds. As of tlie Illinois Caseyville group. such groups become better defined the There is questions as to the proper cor- possibility of applying methods of phy- laelation of the upper part of the Mc- logenetic paleontology becomes increas- Leansboro group in both the Appala- ingly more practical. DESCEIPTION OF NEW MATERIAL NAZOCARPONBenson, ex Scott, 1909 the information l!tiss Benson provided 1909-Scott, D. H., Studies in Fossil Botany, and offer a few additional comments and 2nd ed., pp. 187-8, fig. 78. photograqhs of megasporangia. Both 1918-Benson, M.: Ann. Bot., vol. 32, 1313. 569- I~eClercq(1925) and Koopmaiis (1928) 589, pls. XVII, XVIII. have ciescribed nla~ocarpol~from the Great Coal-ball horizon, in Belgium and Mccxocarpon is a group of plants rep- Holland respectively. resented typically by cones that show certain liistologic and morphologic fea- MU~O~U~~OTZslzorense, ciescribeci by tures. Taxonomically the genus is satis- Miss Benson in 1918 is the genotype. factory since the name is free from ambiguity. Similar cones preserved as MAZOCARPONOEDIPTERNUM sp. 110v. iinpressions or compressions usually are Plates 1-6 best referred to Xigilluriostrobz~s since Hetero~po~ouslycopsid plants, pos- ordinarily such preservation does not sessed of unisex~xal cones. Cones of permit the identification of Mazocarpon. niediuni size, about 12 mm. in diameter Maxocarpon and Xigillurios trobus are and 10 cm. or more in length; pedun- not synonymous because their respective culate ; characteristically deciduous in ciiagnostic features are different, b~xt their entirety. Sporophylls apparently from a biological standpoint the two either verticillate, five or six to a whorl, genera overlap to an as yet undefina- arranged in alternating series, or at- ble degree. Xigillariostrobzcs is more tached in a low spiral. Sporopliplls fair- broadly defined than Maxocarpon, and a ly persistent on the cone axis. Axis 2-3 more diverse array of species is included mm. in diameter, consisting of a narrow in it. It is by no means certain tliat all sclerotic shell less than 200 p thick, species assigned to Xigillnriostrobus are equivalent to the outer cortex. The vas- closely related. $laxocnrpo~~,on the other cular system is centrally placed and hand, is ~xnqaestionablya homogeneous consists of stele and sporophyll traces. group. It is possible that forms previ- Only occasional bits of delicate internal ously assigned to Sigillarios trobus may cortical tissues are preserved. The stele eventually be referred correctly to iia- is somewhat variable in diamete~and xocarpon. iiaxocarpon, having the more in structure; it varies from %-?hmm. precise systematic meaning, is pref era- in diameter and generally appears me- ble to Sigilluriostrobus if a situation dullated with a few scattered central should arise in which choice is permissi- tracheids enclosed by prosencliymatous ble hetween them. "pith" cells; sonietimes the stele has Scott originally publislied the name little medullary tissue and appears as iklccxocarpo~zand credited it to Miss Ben- a solid vascular strand. Traces come son, although her more complete ac- off from it at a long slant and appear count of t,he genus did not appear for to enter the Eo~~rthwhorl of sporophylls several years. Scott stated that ('Maxo- above their point of origin. In their carpon [is] distinguished by the fact horizontal course through the sporophyll tliat the megaspores in the sporangium the trace lies close to the adaxial side of the pedicel; distal to the sporang'0 ium are embedded in a massive parenchyma- there is a well-defined dorsal loop. With- tous tissue ". This single characteristic in the pedicel and lamina, tracheids of will serve to distinguish the genus, since the trace are chiefly scalariform; in a comparable development of intra- the axis, spiral and annular elements sporangial tissue is not known to be make up much of the sporophyll trace. present in any other group. Miss Ben- The mega- and micro-sporangiate son's discussion provides nearly all the cones and sporophylls are similar except detailed information that was lmown for their xporangia. The pedicel is at- of iinxocarpon prior to discovery of the tached at right angles to the axis and present material. Both Scott (1921) has broad thin lamina1 extensions on and I3irmer (1927) have summarized either side. The bulbous dorsal ap- DEXCRIPTIONX 15 pendage or (lieel' ', strengthened with erably thinner in two or three areas on thick sub-dermal sclerenchyma, is a top of the sporangia and below on both noteworthy characteristic of this species. sicles close to the pedicel attachment. The specific name "oediptermm,", i. e., No other mechanism of dehiscence is swollen heel, refers to this feature. The provided. The sporangial interior is lamina proper is exceptionally short filled by parenchymatous tissue which (abo~~t3 mm.), broad, and turned surrounds the eight megaspores on all sharply upward forming about an 80" sicles. Megaspores are large, approxi- angle with the pedicel. A reconstruction mating 2 mm. in diameter, radially of a megasporangiate sporophyll of this symmetrical, varying in form from species is shown in text figure 2. plano-convex to strongly concavo-convex. Spores adorned only by a cellular The nlegasporangiuni provides the c ( ramenturn" borrowed from the intra- significant characteristics identifying the genus and consequently the holotype sporangial tiss~xe;spinous or other ap- of the new1 species is chosen from the pendages absent. Gametophytes are megasporangiate cone material. There present within some of the megaspores. can be no doubt that the associated The sporangia in these instances are microsporan giate and megasporangiate more or less clisorganized and broken. cones belong to the same species. How- A single short-necked pyriforni arche- evey, no organic connection exists be- gonium is formed directly below the tween the different cones, and they are spore apex; the venter is about 250 p inherently different. There is no basis in diameter. for comparison of certain specific de- The holotype of LUaxocarpo~~oedipter- tails (chiefly spores and sporangia) of wrn and of forma mega-Lophorum is that the megasporangiate and microsporangi- illustrated in plate 1, figures 1-4; plate ate cones. Thus, since objective proof 2, figures 2, etc. from coal-ball 136, of of identity is lacking to this degree, a the Illinois Geological Survey collec- ~niiiortaxonomic distinction is adopted tions in U~bana. and cones of the different sexes are r.eferrec1 to separate forms within the Lam SpK species. / J

Forma MEGALOPHORUM, forma nov. P1. 1, figs. 1-4; pl. 2, figs. 1-5; pl. 3, figs. 1-9; pl. 4, figs. 1-5; pl. 5, figs. 2, 6. Cones as previo~~slydescribed, bearing megasporangia. Sporangia, tapering, 3?&-4 mm. broad adjacent to the cone axis; up to 5% mm. broad near the distal end. Sporangia are about 5 mm. long and average about 2.7 mm. high. The greater distal breadth is chiefly clue to the occurrence of keel-like pro- jections of tissue 10~~7on both sides of Ihe megasporangia giving them a somewhat triangular shape in cross-section. FIG. 2.--Reconstruction of sporophyll of These lateral keels flare distally, then Maxocarpon oeclipternu?n forma megaZoph,- turn sharply upward and converge at OTU~.SpK, sporangial keel; Lam, lamina. the upper distal tip of the sporangium to produce a typical up-pointed "toe" Forma MICROPEIORUM, forma nov. effect, as seen in radial section. Spor- PI. 4, figs. 6-8; pl. 5, figs. 1, 3-5. angia are covered wit11 the characteristic Cones, as previously described for prismatic OY palisade layer of cells as this species, bearing niicrosporangia. in Lepidostrobzcs. The prismatic cell Sporangia less inflated than in forma layer varies in thickness, being consid- nzegaloplzorum due chiefly to absence of persistent internal tissue and lack of also cut radially but on the other side lateral sporangial keels. Microsporangia of its center and shows little regularity about 2-2.8 mm. wide, about 4 mm. long of sporangial contents. The dark bodies and 2.5 mm. high. No intra-sporangial shown are more or less distorted mega- tissue is present in the mature microspores lacking their usual regularity of sporangium such as that present in the position. If eight megaspores are pres- megasporangium ; the prismatic wall ent it seems that some of them were layer is less rigid and more or less casual abortive. Although this sporangium (b) distortions often occur. In dehiscence has not attained normal development, a fracture occurs about. halfway up on the sporangi~~mbelow it (c) apparently either side of the sporangium and ex- has grown larger to compensate for this, tends over the top at the distal end. becoming almost spherical. The six This line of fract~~reis equivalent in spores shown in sporangium c are also position to the slight concavity above displaced from their nsual arrangement, the lateral keels of the megasporangia. but the increase in the size of the spor- Usually, the microsporangium is also angium is accompanied by an increase broken from the pedicel; sometimes this jn the amount of intra-sporangial tis- causes another split at the bottom of sue rather than by the development of the sporangium, and sometimes the more spores. The maximum number of spoon-like lower half of the microspo- megaspores was probably eight and rangium remains anbrolien. The only these probably developed ordinarily trace of sterile tissue within the mature from only two original tetrads. The sporangiam is a thin, somewhat varia- manner in which the individual spores ble, but often "T" shaped process at- separated from the tetrad and came to tached radially part way along the pedi- be enclosed in tissue is still an unsolved cel. Immature microsporangia at the problem, but may be d~leto anomalous cone tip show that this is derived from growth of the subarchesporial pad. Hir- the collapsed tissue of the subarchespor- rner's suggestion (1927, p. 284) that the ial pad. Spores are about 60 p in di- eight megaspores developed fmm eight ameter, slightly triangular, trilete, with tetrads with three spores of each tetrad rays extending to the equator. Exosporc totally abortive, is ~~ns~~ppo~tedby any covered with numerous low papillae ; positive evidence and makes the well endospore smooth and thin. At the point developed trilete (haptotypic) structure of each of the three pyramic segments of each mature spore very difficult to of the endospore is a characteristic explain. apical prominence. No endosporal male A normal sporophyll is shown in plate gametophyte has been observed. 1, figure 2 (N Sp) cut in almost perfect Co-types of forma naicrophorz~nz are median section. Its sporanginm, how- the two cones illustrated in plate 5, evel-, is separated from the pedicel and figures 1 and 3 from coal-ball 124 in the apparently was held in place only by Illinois Geological Survey collections. the short upturned lamina. From this and similar examples, it is evident that MORPHOLOGIC FEATURES as the cone broke ap, the sporangia Plates 1 and 2 illustrate the general tended to separate from the pedicels. features of forma megnZophorum. Fig- In Maxocarpon shoreme, the entire ures 1 and 2 of plate 1, and figure 2 of sporopliyll was shed as a unit, so that plate 2 represent parts of approximately the separation of individual sporangia 'adial sections of a fine cone. The three in $1. oedipternum, rather than corn- complete sporangia a, b, c, shown. at the plete sporophylls, may also be talien as left in figare 1, plate I, vary considera- a specific distinguishing character. The bly. The upper sporangium a is cut dorsal loop of the sporopliyll trace with- radially but slightly to one side of the in the b~~lbousheel is plainly shown. center so that the sporangial attachment The trace passes o~~tof the section pros- to the pedicel is missed. Four mega- imally so that it is not shown entering spores are shown in characteristic ar- the axis. However, the proximal portion rangement. The lower sporangium b is of a trace is shown by the second sporophyll above, the lower part of which paratus is seen with the three segments appears at the top of the figure. slightly upraised and the sutures split The slender vertical stele (which is apart. Not all the apical prominence medullated in this cone) is shown in is due to opening of the spores, as there figures 1 and 2 cut on a long slant in is a distinct natural bulge of the spore the cone axis. Numerous outgoing sporo- coat in the apical region. In general, phyll traces can be seen as thin dis- however, the proximal surface is more continuous lines mounting at a steep or less concave, despite this apical con- angle in the inner cortical region which vexity. A scaly "ramentum" which is otherwise nearly devoid of tissue. separates easily from the spore coat generally covers each spore. ,There are no Figures 3 and 4, plate 1, are tangen- spines on the spore coat such as are tial sections of the cone. Figure 3 is characteristic of Maxocarpon shoreme. from a plane quite near the cone axis. The nature of the ramental cover (R) The sporophyll arrangement here sug- is clearly shown on plate 2, figure 1, gests a low spiral phyllotaxy, but this where it is continuous with the intra- appearance may be due to a slight me- sporangial tissue. The cell walls of the chanical flexure. It is not proved that intra~por~ngialtissue adjacent to the the sporophyll arrangement in this group developing megaspores have been im- of plants is inflexible; other specimens pregnated with waxy spore-coat mate- seem more concl~~ivelyin favor of a rial and are more or less incorporated rerticillate arrangement. The section in in the outer part of the spore coat. figure 4 is taken across the sporophylls Thus the rament'um seen on these iso- just proximal to the great dorsal ex- lated spores is different in origin from pansion of the heel. Each of the three the emphytic ornamentation usually sporangia shown has separated from its seen on lycopod megaspores. The spores pedicel, in the manner also shown in themselves must be considered as essen- figure 2. At this level the pedicel and tially levigate. Surface features of iso- its wing-like lateral extensions show con- lated spores freed of the " ramental" siderable irregularity in form. layer are seen on careful inspection to The low position of the tissue-filled be similar to the surface features of lateral keels of the sporangia is shown spores generally identified as Triletes on plate 1, figures 3 and 4; also on (Aplzanoxona ti) rei~zschi. Theref ore in plate 2, figure 4 (SpK). Plate 4, figure Mcleansboro coals, Triletes reiwchi, in 3, shows a sporangium with but one part, is accordingly believed to repre- lateral keel ( Sp'K) . The sporangial keel sent 1Vaxocarpon oedipterm~nz.4s stated turns sharply upward at the distal end in an earlier paper (Schopf, 1938) T. of the sporangium as shown in text rehschi is a generalized form and this figure 2. Radial sections, as on plate 1, species, typically based on isolated figures 1 and 2, and plate 2, figure 2, spores, probably would include several cut the keel near the apex of its distal species if details of the cone struct-ure upturn and permit a somewhat better could be characterized in each instance. visualization of this structure. Female gametophytes are present in The megaspores shown in the sections several of the spores. All cones thus previo~~slydiscussed appear flattened or far discovered which contain such "via- even concavo-convex (cf. plate I, figs. ble" megaspores are in stages of dis- 1-4). Spores as shown on plate 4, fig- integration. A part of one of these ures 2 and 4, are cut obliquely so that cones is shown on plate 4, figure 1. It the proximal concavity is not shown. seems likely that gametophytes develop- Numero~~smegaspores have been iso- ed, as a rule, after the cones had dropped lated from the matrix by dissolving the from their parent plants and were lying calcite in dilute hydrochloric acid, and free in the litter of the coal swamp. these spores illustrate best the original No kinetic mechanism can be recognized spore form. The proximal aspect of TI hich would expel the megaspores from three of these isolated spores is shown the cone or from the sporangium. The on plate 2, figure 5 a-c. The trilete ap- prismatic layer is thin on either side of iLL4ZOCARPON OEDIPTERNUM the pedicel attachment, and this is where attain a diameter of 100 p. Gymnor- the sporangium brealis loose first (com- pern~icarchegonia are generally more pare pl. 1, figs. 2 and 4). TWOor three than twice as large, b~~tit appears that other thin areas, as shown in plate 2, the largest cryptogamic archegonia figure 4 (T), also seem to mark natural known are these from iWuxocarpon. lines of wealmess where brealis in the In two instances a small globular sporangial wall can easily occur. group of 8 to 12 cells was observed The female gametophytes agree in which may represent young embryos general with those of Selaginellu and within apical cavities that may accord- Isoetes except that only a single very ingly correspond to venters of arclie- large archegonium is produced in each gonia after fertilization. These are megaspore. Proximally toward the shown on plate 3, figures 1 and 2. apices and around the inclividual arche- Figure 3 shows the struct~~rein fig~~re gonia the cells are smaller and more 2 at lower magnification. The spore delicate, as shown on plate 4, figure 5, from which figure 1 was obtained is the and also in fig~lres2 and 4. In figure same as that illustrated at lower magni- 2 the gametophyte is somewhat frag- fication on plate 2, figure 3. Since mented within the megaspore coat, but gametophytic tissue is not preserved the tissue that remains has been trans- except near the apex of these spores, formed into material having all the and since the globules of 8 to 12 cells characteristics of fusain and is fairly mentioned show no differentiation of well preserved. A single arcliegoni~m tissues, one cannot be certain of their is also present, although the section il- embryonic nature. If the two respective lustratecl cuts it tangentially and its cellular globules do represent embryos, full diameter is not shown. Plate 4, fig- the original archegonial cavities m~wt we 4 illustrates another megaspore have shrunk by inward proliferation of which is similar in most respects but cells, since both the apical cavities are shows the gradation in gametophytic smaller than in normal prefertilization cell size, distal (largest) to proximal archegonia. The available series of sec- (more delicate cells), the best of those tions demonstrates that the " embry- shown here. This gametophyte appar- onal" group of cells shown in figure 2 ently shrank away from the distal spore is free of any attachment to the wall coat before becoming partly fusainized of the cavity which surrounds it. The aml mineralized. Figures 8 and 9, plate fact that two similar " embryonic ' 3, repyesent a section across the apical globules have been found shows at least prominence of a megaspore and an that these struct~~resshould not be archegonium which is cut above the dismissed as meaningless. middle so that its full diameter is not Microsporangiate cones which are shown. A spherical red humic body, identified as f orma microphorum are somewliat suggestive of an eg'g nucleus, shown on plate 5, figures 1 and 3. The lies in the center of the archegonial first represents a longitudinal and trans- cavity. Fig~~res5, 6, and 7, plate 3, verse section at the tip of a cone. The sliow part of a series of longitudinal cellulose peel from which this photo- sections through an archegonium. Fig- graph was taken extended over both ure 5 iIlustrates a median section which transverse and longitudinal surfaces so shows that the archegoniu is pyriform, that the register of struct~xre in the with a very short neck that protr~des two opposite planes is perfect. Fig~~re slightly into an external cavity, or ves- 3 is a similar peel talien at the base of tibule, just below the spore coat apex. another cone. Although most of the A deposit of dark humic material part- sporangial walls are broken at one or ly fills the venter of the archegoni~m two places, the majority of the micro- and obscures some of the cellular de- spores have remained in place. This is tails. The venters average about 250 ,M fairly common in this material, in con- in transverse diameter, being much trast with the usual condition of preser- larger than those known in other fossil vation of Lepidostrobus in which the OY modern cryptogams, few of which spores usually have been shed. Some MORPHOLOGIC EIEAIVRES 19 microsporangiate cones of Mazocurpon angia a moderate amount of sterile tis- are more fragmented, and the spores sue is found, as shown diagrammatically are more or less completely dispersed. in text figure 3a from a sporangium at Dehiscence of the microsporangia is the tip of a cone. The subarchesporial some~~liatmore regular than in the pad of mature sporangia collapses into megasporangia. *4 fracture occurs on an irregular line of material centrally either side of the microsporangium located in the sporangium which is ( corresponding to a position slightly sometimes "T" shaped as shown in above the lateral keels of the megaspor- figure 6, plate 4 (s). This is connected angium) and crosses around over the to the peclicel along the line of sporan- distal end, as shown by breaks in the gial attachment. The walls in mature sporangial wall in text figures 3b and microsporangia, like the walls in the 3c. It is also common for tlie microsporangia of most other lycopods, are sporangiuni to separate from its pedicel only a single cell-layer thick. There is and split along the line of attachment. little if any more sterile tissue in these It seems probable that tlie microspor- microsporangia than in those of several angiate as well as megasporangiate species of Lepiclosfrobzcs. cones TT-ereintact when shed from the The presence of the ligule is very trees which bore them and that the difficult to ascertain on most of the distribution and association of microsporophylls. Ligules are rarely found, spores with megaspores took place in which is surprising in view of the abnn- the surficial litter of the peat swamp. dant and well-preserved material avail- Isolated microspores are very common able. No ligules hawe yet been founcl in tlie matrix of these Calhoun coal- at the cone tip, and it is certain that balls, and if wind had been an effective the ligules did not function as protec- agent in their dispersal, it does not tive organs for the apical meristem, as seem that the microspore concentration the sporophyll laminae themselves over- would be so great. arch the meristem and provide this pro- Microspores are shown at higher mag- tection (pl. 5, fig. 5). It is still possible nification on plate 5, figure 4. They are the ligule may have functioned in spore- about 60 ,U in diameter, slightly tri- lings during germination stages. Plate angular, with trilete rays extending to 4, figure 7, shows what is probably the the equator. The expospore is papillate, shrunken vestige of a ligule (lig) . The as slio~vnin figure 4a. The endospore distal end of this sporophyll is shown is thin b~~tgenerally distinct. The exo- at lower magnification in figure 8 and spore is commonly torn when the peels is also drawn diagrammatically in text are removed, tlie endospore remaining figure 3b. In some megasporangiate intact, as in figure 4b. The sut~~resare sporophylls there is a suggestion of a carried through the endospore, and at pit distal to the sporangium which map the tip of each of the endosporal pyra- represent a place of ligular attachment. mic segments there is a refractive glo- However, from the evidence now at hand b~deor thickened spot. This is charac- me hesitates to say that tlie ligule is teristic although its significance is un- a constant feature of either megaspor- known. The endospore shows no other angiate or microsporangiate sporophylls. distinctive features. As previously mentioned (p. 14) the The microsporophylls shown in figure sporophyll trace in the pedicel and lam- 3, plate 5, seem unmistakably to be in ina is chiefly composed of scalariform ~erticils. The slightly tangential sec- traclreids. Distal to the sporangial at- tion of the cone apes slio~vnat greater tachment and above the lieel, the trace magnification on plate 5, figure 5, il- curves ciownwarcl abruptly before it lustrates the nearly perfect symmetry turns up to supply the lamina. This on either side of the cone axis. distal downturn of the trace has been In contrast to Maxocurpon shoreme called a "dorsal loop ". Inside the loop and M. pettyczwense, M. oedipternuw the trace expands by the addition of has very little sterile tissue in its ma- scalarif orm transf usion-type tracheicis. ture microsporangia. 111 immatnre spor- These are shown in figtxre 7, plate 4, and are also indicated diagrammatically in text figures 3b and 3c inside the dorsal loop (DL). The trace follows Cone along the upper part of the pedicel Apex but does not enter the ridge of tissue which at-taches the sporangium, nor does there seem to be any special development of transfusion tracheids on the ventral side of this portion of the trace (see plate 6, fig. '7) although food must have been actively transferred along this line during sporangial development. Lack of ventral transfusion tracheids in the sporangial attachment is in con- Stele. trast to th,e condition described for

I , Nuxocnrpm shorense. The traces while 5 mm still in the cone axis contain a large number of characteristic spiral and annular elements such as are shown on plate 6, figure 8. The traces originate from the stele at an acute angle and connect there with exarch s~iraland a.nn~~larpro'toxylem elements. Plate 6, Lam. shows an extreme tangential section of a stele which includes one of these protoxylem groups. The stelar Axis metaxylem is made up of somewhat larger scalariform elements as shown in figu~es4, 6, 9, and 10 of plate 6. In many specimens the stele contains a pith7 coinposed of prosencliymatous cells (fig. 6). Generally a few isolated trach- ;h rl\p eids, apparently annular, are dispersed in the central tissue of t,hese steles (figs. 9 and 10). In some cones the zone of metaxylem. is relatively thick with a corresponding decrease in the amount of med~~llarytissue (fig. 4), and occasionally the pith is absent (fig. 3). Th,e primary pro'toxylem points seen i11 cross- sections vary from about 10 to 12. Their arrmgeinent indicates a spiral sequence in some specimens but more. commonly a verticillate arrangement. (fig. 10). There seems no reason for assuming that the number of protoxylem points is invaria- ble or that the phyllotactic arrangement of sporoph ylls is inflexible.

FIG. 3a.-Outline tracing of immature mi- with wall broken (fract.), its attachment to crosporophyll at cone tip. Dark borders in- the pedicel (Ped.) ; the sporophyll trace (Sp. dicate the extent of subdermal sclerotic tissue Trace) with its dorsal loop (DL) ; the ligule and sporophyll trace. Thin-walled tissue (Lig.) , lamina (Lam.), and dorsal heel (H). stippled. s=subarchesporial pad. From C. B. From C. B. 124 E (32). 124 E (27). c.-Outline tracing of median section of b.-Outline tracing of median section of ripe sporophyll as given above in b. The lam- ripened microsporophyll showing sporangium ina is slightly longer than usual. From C. B. (Sporang.) still containing microscopes but 124 E (27). FIG.4.-Segment of peduncle of ( ?) Mazocarpon oeclipternum. Drawing was prepared from a peel taken simultaneously from tangential and transverse surfaces as shown. Proto- and metaxylem of stele shown in black; medullary tissue lined; cortical tissue stippled. Steles are separately drawn at higher magnification at the left to show protoxylem points. From C. B. 136 A5 (17). The peduncle of a cone is illustrated than the distal end. The dimensions of on plate 6, figure 2, and in text figure t'he peduncle increase slightly away 4. The axis illustrated was not found from the proximal end." greater attached to a cone but the close simil- n~mibe~of bract bases are transected arity of its stelar structure to that of at the distal end and the stele is some- less well preserved but attached ped- what larger there with more protoxylem uncles permits little clo~~btas to its re- points. Orientation is proved by the lation. The stele of another peduncle manner of attachment of the bracts. is shown at greater magnification on Steles from both ends are diagrammatic- plate 6, figure 1. Were it not for the ally representea at higher magnification stelar similarity, there might be some at the left of the text figure. The pith donbt as to the identification of the ped- area is invaded somewhat by medullary uncle because of differences in the cor- tracheicls as in the cone axis. tical tissue. The cortical tissue is rather A more complete acco~xntof the varia- thick at the position illustrated by fignre tions in the peduncle cannot be pre- 2 and shows prominent parichnoidal sented at this time. Additional study is cavities. Adjacent to the cone, how- needed since the structure of the ped- ever, there seems to be a definite transi- uncle is particularly important in estab- tion to the structure of the cone axis; lishing the relationship of Maxocarpoln the pectuncle is smaller than in figure with better known genera identified on 2, has no bracts, and the outer surface the basis of stem structure. It is a is quite regular. At this higher position matter of interest that a ligule appears close to the cone, sclerencliyma is pres- to be present in the axil of one bract ent around the periphery which presum- sliown in nearly median section in text ably merges proximad with the thick figure 4. outer cortical tissue of the peduncle. 5The form that Lesquercus first named Lepidos- trobus Zacoei (1880 13. 439) later referred to In the cone axis the thicli: sclerotic cor- Lz~cogodites (1884 11' 780) wdich is illustrated in tex is largely absent. The peduncle is TW~.I11 of the ~oklkloral(pl. CVII. fig. 1) is of interest. It appears to have no connection with nearly bare acljacent to the cone, but either Lepidostrobus or L?jcopodites and instead is proximally it bears a n~~mberof short properly referable to Sigillariostrobus. This genus, as mentioned later. comnares favorablv in swpral bracts in an irregular spiral arrange- respects and is intimateiy related to ~laxocarpon~ Lesqucreux's specimen apparently shows the com- ment as shown by the segment illns- plete peduncle which in this case is devoid of t,rated in text figure 4. The bracts, as bracts-except for a few near the base of the cone. The peduncle varies in diameter frorn about 7% shown by transverse sections of the two mm. at the prosinla1 end (wherc it presumably was attached to the trunk of the tree) to about ends of this segment, obviously vary in 4 rnm. near thc middle from whence it again ea- pands to about S mm. in diameter at the cone their arrangement. The drawing (text base. In all it is abcut 14 cm. in length. The fig. 4) was prepared from a peel which peduncles of Sigillariostrobus goldenbergi (cf. Zeiller, 1884. pl. 12, fig. 5) and of other species of coveyed both of the transverse surfaces *rig.zlla?-iostrobzls, while often less complete, also show some indication of a similarly inconstant and one tangential surface so that the diameter. The seemingly anonlalous feature shown by a sector of peduncle of Maxocar-pon oedipteraunt structure in both directions is contin- in text figure 4, with a distal diameter greater no~~slyrelated, b~~tthe proximal end is than the proximal may thus be in general agrce- rnent with peduncles of other cones of sigillarian sectioned at a deeper tangential level affinity. COMPARISON OF 144. OEDIPTER- of the megasporanginm which is " more ATUM WITH OTHER SPECIES highly ciifferentiateci ". JIiss Benson's OF IMAZOCARPON illustrations of Maxocarpon cashii (her figs. 15, 16, and 17) also seem to indi- ilIazocurpo~z p e t t y c 26 7- e ?z s e Eenson cate a form somewhat smaller than (1918) .-This species from the Lower Maxocurpo.iz slzoreme. However, Maxo- Carboniferous Calciferous Sandstone is carpon cas1zi.l is not well enough charac- geologically the oldest species lrnown. terized at present to offer any adequate Information in regard to it is scant basis for comparison with H.oeclipter- il3enson 1908; 1918, p. 578 ; and Scott, 1221112 beyond that presented with regard 1920, p. 216). The only illustrations are to il/luxocarpon shoreme which, in any the drawjngs given by Uiss Eenson in event, is very closely related to it. connection with her discussion of the $1 axocarpolz shoreme.-This species is sporangiophore (New Phyt. fig. 25, much better lrnosvn than either of the 1908j . The chief distinction upon which other English species, since it is the this species is based is that the apiculate form chiefly dealt with in Miss Benson's megaspores are more numerous than in paper of 1918. It was obtained from the 11. shorense and other species. From Great Coal-ball horizon (Halifax Hard JIiss Benson's figures it may also be Bed) and from the Hough Hill and inferred that the definite arrangement Stalybridge coal ~vliichis slightly older. of megaspores in the sporangium and It also has been recorded comparatively the spore form characteristic of the from the Finef ra~l-Nebenbankcoal in Pennsylvanian species, had not yet been Limberg, Holland, by Koopmans (1928, establisheci when the Calciferous Sand- p. 21). It thus appears to be a fairly stone sediments were deposited. A large common and widespread form which, amonnt of iiitra~po~angialtissue is defi- as far as is lrno.cvn, is restricted to the nitely shown for both megasporangia lower Westphalian A. A detailed de- and microsporangia of $1. pettyczbre/lzse. scription of H.shoreme has been pye- The niegasporangium apparently lacks pared, summarized from Miss Benson 's lateral keels, and this also may be an account (1918) and given below, in identifying characteristic. order that a close comparison can be Miss Benson notes later (1918, foot- made with $1. oediptermnz previously note. p. 579) that the micr~spo~angi~~mdescribed. Where measurements were of M. pettyczwcnse (1908, fig. 25b) is not originally provided by Miss Benson, magnified 30 times, whereas the mega- they have been obtained as far as possi- sporanginm (fig. %a, 1908) is magni- ble by measurement from the published fied 39 times, but the two are cirawn illustrations. Attention is called to a as if they were the same size. This is few discrepancies and to points where a difference in actual linear dimensions actciitional information would be helpful. of about 23 per cent, the micr~spo~an- Cones pedunculate, 13.5 mm. in diameter, gium being the larger. Whether this is more than 8 cm. long. It is not definitely ,211 actual size difference or whether the known whether or not cones were unisexual. sections vere merely from different tan- Sporophylls are characteristically deciduous gential positions on the cone cannot be in their entirety; arrangement on the cone - - judged. axis is stated to be in a "close spiral" but the arrangement also may have been verti- Mnooccrrpo~?mshii (slide 472A, Man- cillate. Cone peduncle and axis somewhat chester Collections) .-This species is hexagonal, about 3 mm. in diameter, outer probably of Lower Coal' Measures (up- sclerotic tissue relatively thick (slightly per Lanarlrian) age, although the source under a millimeter). Mesarch sporophyll cf the type specimen is not definitely traces and associated tissues pass through li-nown. It is said to be distinguished sclerotic tissue on a rather long slant. Stele apparently medullated, about 1/2 mm. in di- from Maxocnrpon shorense by the sporo- ameter, with projecting protoxylem points; pliyll traces in the cone axis vhich "are other details unknown. Sporophyll pedicels surromided by a sheath as they pass diminish in width to about 1 mm. at their ont through the lacunar middle cortex" point of attachment to the cone axis. Pedi- and by transfusion tissue at the base cel extends radially for about 5 mm. and SPECIFIC COXPARISONX merges there with the upturned lamina. Lamina rises to the third rank above, hence was probably about 10 mm. long. Lamina is about 6 mm. broad and spoon-shaped at its base; lamina1 outgrowths 011 either side of the pedicel are not as broad as in fM. oeclip- tewzz~nt. Dorsal heel nearly lacking; sporophyll is thickened at the juncture of lamina and pedicel but extends downward only about 8/10 mm. below the plane of tlie pedicel. (Cf. p. 580, op. cit. It is evidently a mistake where it is stated, op. cit. p. 576, that this "convex cushion might be 8 mm. below the plane of the keel.") Megasporan- gium is about 5 mm. in length, 2.6 mm. in height, and attached to a ventral ridge of the pedicel. Traces of a ligule are reported situated in the sinus distal to the sparan- gium. The sporophyll trace extends the length of the ventral ridge instead of in the pedicel itself and recurves downward at the distal end to enter and supply the lamina. The sporangium is somewhat nar- rower adjacent to the axis and broader clis- tally. Externally it is marked by a keel ("sporangial lamella") extending on the sides and around the distal tip of the sporangium. Position of the keel on the sides of the sporangium is somewhat uncertain. Miss Benson's much copied text figure 1 (03. cit. p. 571) shows the keel recurved upwards and only carried toward the axis about mid- way, high on the side of the sporangium. Her photographs of tangential sporangium sections (figs. 1 and 16, pls. XVII and XVIII, op. cit.) show the keel low on the sides. It would seem probable that the photographs show its position more accurately. The sporangium and its keel are covered externally with a characteristic prismatic cell layer. AS many as eight large (about 2 mm. diameter), radially symmetrical, plano- or concavo-convex, strongly apiculate megaspores are contained in each megasporangium. The spores are in a definite arrangement around the periphery, with their apices oriented toward the center of the sporangium. Intrasporangial tissue fills the central part of the sporangium, more or less en- closes each of the megaspores, and margin- ally lends rigidity to the sporangial wall. External to the megaspores this tissue is only a few cells thick except in spore in- terstices and in the sporangial keel. Some megaspores, either isolated or in partially disintegrated sporangia, possess gametophytes. At least two archegonia may be produced subjacent to the spore apex. From FIG. 5.-Diagrammatic representation of Miss Benson's plate XVII, figure 3 (op. cit.) Mnxocar'pon oedipternunz; a. megasporophyll the venters appear to be at least 200 p in in transverse section near the middle; b, por- diameter. tion of megasporangiate cone in longituclinal section; c. diagrammatic representation of The details of the male cones (or portions Maxocarpon shovense; based an information of cones?) and of the microsporangia are summarized from Miss Benson (1918). Dia- much less satisfactorily known. It seems grams a-c drawn to the same scale. OEDIPTERNUN that spores were produced in pockets of mas- the sporangiophoric interpretation once sive intrasporangial tissue. The single micro- advanced by Miss Benson (1908). The sporophyll found was evidently immature centrally located intrasporangial tissue since the spores were still in tetrads. Tissue- filled sporangial keels are present. These in the megasporangium of M. oedipter- features and the association of this speci- num, which may be compared with the men with megasporangiate material in coal- subarchesporial pad of modern lycopcds, balls from Shore, Lancashire, are the basis shows a slight alignment of cells radiat- for assigning it to Maxoca~ponshorense. ir,g from the base. This may be a result The features of the megasporangiate of growth of intrasporangial tissue in cone of Maxocurpon shoreme (text fig. the direction of the nutritional gradient 5c) and of a similar cone of M. oedipter- while the young sporangiom was actively enlarging. ?zlinz (text fig. 5b) have been incorporated in diagrammatic longitudinal sec- The lerigate megaspores of Maxocar- tions for direct comparison. Besides the po~2oeclipte4-wrn are distinct from the great difference in thiclmess of the axial apiculate spores of M. slzoreme. Proba- outer cortex and in length of their re- bly of greater significance is the fact spective sporophyll laminae, the divers- that more than one archegonium may ity in spacing of sporopliylls may be be produced within a single megaspore notecl. slzorense is here depicted with of the English species. M. oedipternzm the sporopliylls in a "close spiral" and has been found in about a dozen in- the distal "convex cushion" (heel) stances to have only a single mry large close above the spol-angium below. The archegonium placed directly below the sporophylls of M. oedipternz~rnare more spore apex. This is a rather surprising widely and alternately spaced. Wide constancy in a cliaracter which is vari- spacing of the sporophylls is apparently able in modern forms. Although it is connected wit11 formation of the large a member of the Paleozoic flora it seems dorsal heel of $1. oedipternum. No more advanced and specialized in this causal explanation for this phenomenon feature than either modern Xelaginella can be advanced at present. The heel or Isoetes. The large size of the arche- serves to make the cone more rigid (as gonia also is probably a specialized fea- it does in Lycopodizm cerwuzcrn, see ture. The gametophyte and archegonia Lang, 1908) but if the sporophylls were are far better preserved in M. oeclipter- more closely mounted on the axis, as in qlunz than are those from any other M. shoreme,. presumably the same de- Paleozoic form now known. gree of rigidity would be achieved with- The microsporangiate cones of 1W. out a dorsal heel. oedipternzcrn are considerably different There seems to be little essential dif- from those ascribed to M. slzorense. They ference between the megasporangia of dif er little from microsporangiate M. shore72se and M. oediptern.unz. The tions of cones of Lepidostrobz~s, the latter species, however, lacks the up- chief specific distinction apparently be- stancling ventral pedicel ridge which ing the broad lateral laminae of the attaches the sporangium of M. slzorense. pedicel in Maxocctrpo.rz oedipterm~m; the In the new species the vascular trace pedicel of Lepidostrobzis sporophylls is, runs close to the top of the pedicel for in comparison, very contracted. The part of its length b~ltcan not be said microspores of both M. oedipterwwm to leave the pedicel. Thus far no vas- and M. shorense are exceptionally large cularization of the base of the sporan- for lycopocl microspores. Whether fea- gium has been noted such as was re- tures other than size are similar is in- ported for Maxoccrrpon cashii and in determinable at present because the iW. lesse~.degree foY M. slzorense. Conse- shormse microspores were all in tetrads qneiitly, no additional support is given and lacked their mature ornamentation.

I GROTIP RELAY'IONSHIPX 25

RELATION OF 1MAZOCARPON TO AFFILIATED GROUPS OF PLANTS

The genera to be considered are: quence represented by the sedimentary (1) Xigillal-in, a group of plants identi- strata. St~tdyof the abundant mega- fied by diagnostic characteristics of spores will aid greatly. In the past, their stems ; (2) Xiyillariostrobus, a sigillarian fructifications have been group of plants identified by certain identified less frequently than their features of their cones, generally dis- stems, anct it has been a question cernable when preserved as impressions whether some of them were most inti- and coalified compressions; and (3) one mately allied with Lepidostrobus and section of the genus Triletes, the Aphn- other lepidodendrids rather than the no~omti,a group of lycopocts identified sigillarians. If this were the case, an by ccrtain characteristics of their iso- interlocking phylogenetic relationship lated megaspores. 3Inxocarpo~?xis a group between the lepidodendrids anct sigillar- of plants identified by certain special- ians might be indicated. The two groups ized characteristics of cones and spo- are for tlie most part easily distinguish- rangia, which may be distinguished only eci by characters of the leaf bolsters, when dl preserved. The groups over- b~~tthere has always been some question lap in a biological sense and can be whether these distinctions were of ac- presented as members of the Siyillar- tual generic importance, and if so, at iaceae during a considerable par-.t of what point in the geological history Carbonif ero~~stime. However, the de- generic segregation took place. The gree of overlap between the genera or presence of Hccxocaspon at a position species is not precisely definable. The rather high in the Pennsylvanian sliows idationships of the late Devonian and that tlie characters which distinguish early JlIississippian antecedants are ob- Maxocarpon from Lepidostrobus were scure, and post-Carboniferous represen- important and persistent, and shows tatives are also inadequately l-aown. that direct phyletic connection between Chiefly because of the inadequacy of these two lines in Pennsylvanian time knowlectge of specific interrelationships is improbable. It is more likely that during ~enns~haniantime and generic the two groups diverged in the early and s~~pragenericinterrelationships dur- Mississippian. ing the late Devonian and early Car- boniferous time it appears necessary to In the following discussion, impor- classify the diverse fossils separately, tant characters in-classification of -the in different specific and generic groups sigillarian alliance are considereci. The at least. Treated thus, the minor stages object is to illustrate the relationship of of the evolutionary sequence may be these forms in the light of reconsidera- cljscussed more readily and accurately; tion of certain of the significant bio- nomenclatorial confusion can be reduced characters. It seems that more emphasis to a minilnun1 became probable interrela- may reasonably be placed on some of tionships are referred to more precisely. them, such as mode of fructification and character of the megaspores, than has Information obtained from the study been generally recognized. On the other of Maxocnrpo~~~oedipternwn supports hand, the characters of cone phyllotaxis the belief that the different genera men- appear to have been overemphasized. tioned above are all members of an intimately related series. It seems that The manner in which the cones are the major. line of phylogenetic affinity borne on these plants seems to be a is reasonably certain even tho~~ghthe character of major importance in defi- minor stages of evolution are imperfect- nition of the sigillarian alliance. Both ly 11nown. The object of further study Mc~xoccrrpo~zand Sigillariostrobzcs cones should be the recognition of these minor a,re peclunculate, and stems of Sigillariu stages of the evolutionary sequence, lrey- bore fr~~ctificationson the main trunks ing them carefully with the time se- by means of peduncles. A primary 26 GROUP RELATIOXXHIP8 characteristic of Xigillariostrobus, dis- Information is scant in regard to the tinguishing it from Lepidostrobus, is fruiting habit of Lower Carboniferous that cones in the latter genus are term- sigillarians. It TTTOLI~~be expected that inally attached to ordinary leafy twigs, at some time in the early history of the wliereas in Xigillur iostrobus the cones gro~~ps,specialized cone-bearing pecl- are borne on the specialized peduncles. uncles woulcl be rn~chless in evidence. Tlie general correlation of such cones No knowledge of the cone axis or ped- with sigillarian stem,s showing the scars ~ncleof Mmocarpoqz pettycureme is here cone peduncles were formerly at- available. If it slio~ldprove to be non- tached is aclequately supporteci. At a pedunculate, its generic segregation few horizons (cf. Zeiller 1884) even a from Maxoccwpo~z might be advisable. specific correlation of stems and cones It is evident that the fruiting habit of has been attempted. The specific evi- Pennsylvanian sigillarians is a 1ieritahle &nee is not altogether conclusive, how- and c~nsistent characteristic wliicli is ever, and even if it were, the pertinent at least of generic significance. question as to the duration in coinci- Stems of the sigillarians may not indi- dence of certain specific features of the cate conclusively the mode of fr~~ctifi- cones with other specific features of the cation, clue to the ~mequaldistribution stems would still be unanswered. The of peduncle scars. Consequently this correlation of Maxocnrpon wit11 Sigil- character is of less practical value in /aria, is based on evidence comparable classification of stem specimens, but the to that wliich applies to Xigillariostrobz~s. peduncle is often shown by good speci- The manner in which cones of Lepi- mens of cones and is more useful in dostrobzcs are borne is similar to that their classification. found in modern flelaginella and more Proof of the real overlapping rela- ad~anceclspecies of Lycopodiunz. This tionship of Xigillariostrobus ~7jtliXioil- iilocle of fructification nevertheless is 7uricc has been most convincingly shown far more primitive, so far as relative by Zeiller. Cone peduncles bearing aci- specialization is concerned, than the cular bracts and bract-scars which re- pedunculate manner of fructification semblecl those on certain associated Xig- noted in the sigillarians. Va~iationsof i17aria stems seem to be fairly conclu- this sort are recognized as important sive. It now appears (relying on de- wherever they are noted in study of scriptions extending over about a cen- modern plants ; they probably are sim- tury) that more emphasis can be plaecci ilarly reliable indicators of specialjza- on lack of conflicting evidence than on tion in the Paleozoic flora. Tlie special- the positive evidence wliich supports ized fruiting habit of Pennsylvanian this general conclusion. Existing evi- sigillarians seems well established and, dence is based on association and on in conjunction with otlier advanced fea- resemblance between peduncle bract- tures, may be talren to indicate that this scars and stem leaf-scars-a comparison sigillarian alliance represents an entire- which probably is not altogether satis- ly distinct group of lycopods during the factory because the bracts and leaves Pennsylvanian period. were not entirely similar and no clo~~bt Whenever evident, peduncle scars produced cicatrices ~7hichwere some- generally occur abundantly in short TI-hat different, even on the same plant. zones upon the stems of Xigillaria. This Proof of a similar relationship be- may be talren to indicate some sort of tween Maxocarpon and Xigillariu is de- periodicity in fruiting. Whether it was rived chiefly from comparison of pe- coordinated with climatic or seasonal duncular steles preserved within sigil- periodicity, like the growth ring special- lariaii stems and in Mccxocarpo~z cone ization of modern plants, is -~~nknown, axes and peduncles. This relationship bnt it is reasonable to suppose that it in no way conflicts wit11 otlier informa- was at least connected indirectly, indi- tion pertaining to the relationship of cating specialization which is not as dis- Xigillariostrobz~s. The basis for consid- tinctly shown by other groups of Pale- ering that Maxocarpoqz possesses the ozoic lycopods. same sort of relation to Sigillaria that XTGILLARIA AND MAZOCARPON 27

Siyillariostrobus does, is best indicated cellently ill~~strated,but it seems to by reference to the few important have been overloolied by later authors. papers which describe the structure of flirmer (1927) makes no reference to peduncle steles within petrified stems of it. Miss Calder (1934) also overlooliecl Xigillaria. it in describing two sections from the Kidston collection vhich seem to have PEDUNCULAR STELES OF been taken from tlie same Colne speci- SIGILLARL4 AND men. The collection data given by Miss fVAZOCARPON Calder agrees with that previously In 1926 Hagkne described a section given by Hagbe. She reports that the of a ribbed sigillarian stem from the external characters of this stem were paleobotanical collections of the Uni- exhibited prior to sectioning, and Xr. versity of Lille. This specimen appar- XIemingway informed her that its iclen- ently had been collected and prepared tification as Xiyjllariu eleyaw was con- by Hemingway in England. The collec- firmed at that time by Kidston. Miss tion locality was given as "Colne, Lan- Calder's description in the main agrees cashire," from the horizon of the I-Iali- with that of Hagdne. However, she fax I-Iard Bed coal,6 and Hemingway describes the solid stelar appendages as had labeled it "Xi'yillaria elegans". This pertaining to cone peduncles and is stem is unique in that it is one member undecided as to the nature of the small of the Fav~~lariansection in which the medullated steles; she makes no ref- rather large stele does not possess any erence to Maxocarpo~z. It seems un- secondary wood, and further, in that a fortunate that sections of this excellent large number of small steles, some of specimen were allowed to become sep- which are solid and others medullated, arated. Not only was there duplication surround the main central cylinder. of effort, but neither authoY was able N~xmerousleaf traces, single and bar-like to make a first-hand evaluation of all near the stele but double in the inner the evidence. Probably additional in- cortex, are also present. Characteristic formation coulcl have been presented sigillarian leaves with corresponcling had this been possible. double vascular strands are also asso- Graham (1935, pp. 158-161) described ciated i11 the same section. The pednnc- a stem from Calhoun coal-balls which rdar steles are of chief interest, for from he assigned to Xigillaricc approximata ihem Haghe concludes (op. cit., p. Font. et I. C. White. Peduncular non- 113, f~eetranslation) that "this speci- mecl~~llateclsteles are quite numerous men both establishes the structure of in sections of this stein but Graham re- the bundles destined for f ructiferous ported none of the inednllated type of peduncles and confirms the relationship -vascular cylinders found in Maxocarpon bctwcelz the genus MAZOCARPONand the oedipternunz. The solid steles he de- qelzzcs SIGILLARIA.". I-Iis concl~xsionap- scribed are somewhat smaller than the parently is based on the close agree- solid type steles also present in 142. ment between tlie medullated peduncle oediytcrnum cone peduncles. Some of steles shown in 11% section and the ped- the nlaxocarpolz oedipter~zu~~zcones pos- uncle stele in the Maxocarpo~~sIzore.~z.se sess a solid stele, but there is little cone axis illustrated at low magnifica- evidence now that specifically similar tion by Benson in 1918. There also is cones were borne by Graham's Xigillaria a good general resemblance between the approxinzata, even though both species inedullated steles adequately figured by are from the same horizon. The stem Haghe and those in Maxocarpon oedip- struct~~resdescribed by Graham agree t erlzunz. in general with those first reported from Hagdne's paper is significant and ex- Siyillariu elegalzs by Kidston (1904), but probably internal as well as definite and Watson indicate that coal-balls external differences can be found. occur at Cohe, Lancashire, in a coal below the "First Grit' and presumably different fro111 the Ilard Eed horizon. It is thus uncertain. to the The histological structure of Xigillaria author at anv rate whether the Colne Sigillal-ia degans (not to be conf~~sedwith tlie irs from the ~i-eat~bal-ball horizon or one slightly lower in the Lanarkian. Permian form, Xiyillaria nze~zardiwhich 28 GROUP RELATIONSHIP8 was described as " S. eleya.lzs" by Brong- teristics of their cones and those ident,i- niart in 1839) was first described in fieci chiefly on characteristics of their adequate detail by Kidston in 1905 from stems. In each group, other more stable a specimen found at tlie Great Coal- characteristics are present and serve ball horizon in England (the same as hest as means of specific discrimination. Buxocarpon shorense). The peduncnlar steles described within the stem were RELATION OF MAZOCAIEPON apparently not similar to those in speci- AND SIGILLARIOSTROBUS mens of Jf. sJzorense, and no comparison In view of the similar relationship has been made between tlie structures n-hich has been suggested between both of the two. Kiclston's description was of these genera ancl the genus Rigillaria drawn from sections of only two ped- it may be expected that the relationship uncles, and it seems that the Colne between Maxocarpon and Sigillariostro- specimen with many pecluncular steles bus is partic~da&yintimate and that provicles a more accurate picture of generic synonymy might exist. The the variation possible in these structures. present evidence favors this interpreta- Apparently none of Kidstoil's original tion; nevertheless, if we aye to main- sections passed directly through a zone tain precision in the application of nom- of the stem whicli bore numerous cones. enclature, it is impractical to assign all It woulcl seem that the clifferences be- of the species classified in both groups tween the peduilcular steles of Kiclston's to any one generic group. On the other specimen are easily reconciled with those hand, it WOLI~~seem justified to ~~nite shown by fMaxocarpon now that both them in some larger group, such as a solid and inedullated steles are known tribe. As stated above, Maxocarpo~z is in the later genus. more precisely definable and is presurna- bly therefore a more satisfactory taxo- Naaocc~rponoedipternum shorn that nomic group. Naxocarpolz may have both solid and Miss Bellson (1918) has previously medullated steles within the limits of discussed some of the evidence for be- the same species; the Colne SigiZ7c~ria lieving Maxocarpo.n and Sigillariostrobzcs shows that both types of peduncular rery closely related and has compared steles may even be formed within the Maxocarpo?z shorense with Sigillarios- same plant. The presence of a solid frobus ciliatus, 8.rhonzbibracteatus, S. type of peduncular stele in Kidston 's tieghemi, etc. In view of the additional original specimen of Siyillaria elegnm information made available in Mnxo- and in Graham's Xigillaria approxinzatu carpon oedipterszz~nz, the relationship is not discordant with the belief that between the two genera may be reexam- LWc~xocarpolztype of cones were boiane ined with reference to a few important by Xigillaria. In the absence of conflict characters, and further discussion may in these more precise characters and in be presented concerning certain species the agwernent of other more general of Xiyillariostrobzcs, chiefly those de- information, the fact of a generic ovev- scyibed since Miss Benson's paper ap- lap seems suEciently founded. On the peared. other hanci, there is no very convincing The diagnosis of Sigillariostrobus is specific agreement in pecluncular struc- still subject to differences in interpreta- tures of any of the species of Xigillaria tion. By many the name is xed to or Maxocarpo?z. This is not surprising designate cones or cone fragments which in view of the few descriptions of f%!axo- are supposed to correlate with Xigillaria. carpol?, and other sigillariaii cone ped- But a scientific nomenclat~~remay not uncles which have been published. The be based on s~~ppositions,and at least inherent variation in peduncular struc- some of the specimens assigned to this ture may in itself be regarded as a genus in the past must be considered generic character, and SLICSI variation in problematic or identifiable only to some any event renders specific correlations group having broader affinity than more difficult. This emphasizes the Xiyillariostrobzcs. necessity of classifying in separate A cardinal point in the identification groups the fossils identified by charac- of SigiZlariostrobus is the peclunculate SIGILLARIOSTROBUS 29 mode of fructification, a cliaracteristic ticillate. Verticillate arrangement in whose importance has been emphasized Lepidostrobzcs is harder to establish than There are certain other features which in Sigillariostrobz~s or Mazocarpo~be- also must be more or less definitely cause the orthostiches commonly ap- included in the diagnosis of this genus pear to be more numerous. Still in the kr~tnone of them seem entirely essential, lepidostrobid forms mentioned, there The cones are of meciium to large size. seems no occasion to doubt that the The sporophylls are often apparently sporophylls are in vertici1s.s A11 these in ~erticilsand, so far as is known are from the Lower Carboniferousg now, they appear to be unisexual. The which may be a point of some signifi- megaspores appear to agree with those cance. Most Pennsylvanian species of of the Apha?zoxonati section of Triletes. Lepidostrobz~s seem to have a spiral In Schiinper 'a original ciescrip tion of phyllotaxy. BLI~in any event there is Sigillariostrobus (1870) he assumed that no direct relationship apparent either the smaller of the spores were micro- between verticillate species of Lepidos- spores altliough they were about a milli- frohz~sand verticillate species of Siyil- meter in diameter. Conseq~~entlylie lurios-lrohzcs or between Lepidostrobus eonsictered the cones of Sigillariostrobz~s and Maxocarpon. It is therefore im- lieterosporous. Several authors have possible to consider this character of commented that all the spores described essential diagnostic significance. by Schimper are probably megaspores, It should also be pointed OLI~ that a and this is apparently the case because low spiral phyllotaxy may, under some features of even the smallest of the conditions of preservation, simulate ver- spores he mentions agree with lrnown ticillate arrangement or vice versa. The megaspores, and of all the lycopod mi- arrangement of sporophylls reported maspores linown none exceed 1/10 the for idlazocarpo~shorense may easily be diameter of the " microspores ) ' Schim- as "verticillate" as some specimens of per observed. Siyillariostrobus in which a whorled So far as size and general habit phyllotaxy is confidently reported. Even characteristics are concerned, the cones if the possibility of error in determina- of Sigillariostrobzls are not different tion of phyllotaxy in Sigillariostrobz~s from niiraxocarpo?~. The cones of Haxo- is disco~~nted,the possibility of devia- carpon thus far described are all smaller tion from a strictly whorled to a low than the largest of Siyillariostrobzcs spiral arrangement of sporophylls must species, h~~tthe majority shorn marked always be borne in mind when dealing similarity if allowaiice is rnacie for dif- with this group of plants. Specimens of ferences in preservation. Mazocarpon, oedipternwn are illustrated Bochenslii (1936, p. 230) has suggest- which may represent both types. Hom- ed that verticillate arrangement of ever, so far as phyllotaxy is concerneci, sporophylls (in addition to their pect- iiazocnrpon and Sigillariostrobzcs here unculate characteristic) may also be a have no points in significant conflict. diagnostic feature of Sigillariostrobus. There is probably a m~lchgreater ten- There is considerable evidence that dency towarcis verticillate arrangement cones of both Maxocarpo.t2 and XigiZZari- ir, both Sigillariostrobus and Muxocarpo?t %pecies of Botlzrostrohus are also described as than in Lepidostrobus. This character verticillate. Wirmer (1927. p. 230) says Lepidostrobus cannot be consickred diagnostic however, broz~niiis from the middle Upper Carboniferous since Zeiller (1914) reports a verticillate but this is an error. The geologic position of several noted specimens of L. brow?zii (including arrangement of sporophylls in Lepidos- the holotype) is unknown because they were sec- ondarily derived from glacial deposits. Zeiller trobzcs browg~ii,and Binney (1871) has (1914) gives the age of several specinlens whose also illustrated specimens ~liichare ver- source is known as lower Dinantian, l.e., the lower part of thg Lower Carboniferous. and Read and Cameell (1939) suggest that some of them TKidston (1911 11. 182) has considered the may poss~bly even be from beds of uppermost Ulode,zdron condition of Clathrarian sigillariana Dlevonian age. The source of L fische.1-i Scott and indicative of the presence of sessile concs in this Jeffrey, (the name later changed to Le&dostrobus section (in part) ; Sigillaricc discophora which he ke?ztuck~/ensisby Scott because "fischeri" mas pre- cites is placed by several authors in the separate occupied) also is listed erroneously by Hirmer : genus Tilodend?-on, and in any event Watson (1914) this species comes from the Xcw Albany shale has shown that Ulodendron type scars are not which Read and Campbell (1939) believe also is caused by sessile concs. uppermost Devonian. 30 GROUP RELATIONSHIYX ostrobzu are generally unisexual. In whorl. This verticillate arrangement is this connection it is more pertinent to apprently the feature which deter- cliscuss the few reports in which cones mined its classification under Siyillari- of Xigillariostrobzcs have been consider- ostrobus. No peduncle is present, and ecl bisexual than the more numerous Miss LeClercq describes the cone in her records in which spores of one type only cliagnosis (op. cit. p. 168) as sessile. (generally megaspores) were reported. From the specimen as it is illnstratecl Seldom has it been possible to prove the one cannot be sure that the cone was nnisexual nature of the cones conclus- actually sessile, but if it was it cannot ively, although Bochenslii ( 1936 ) dem- be placed in Sigillciriostrobzls but must onstrated that cones of Sigillariostrobus be placed in Lepidostrobzcs instead (see cxnmzockii are nndoubtedly unisexual. discussion of peduncle on p. 26). With It is probable that extensive use of sim- the exception of its strict verticillate ilar maceration methods will prove the phyllotasy it conforms better with Lepi- point more conclusively for other species. dostrobus, and this character is by no In the meantime, the lack of substantial means cliagnostic of Xigillcwiostrobzcs. reports of bisexual cones of Sigillarios- Miss LeClercq (op. cit. p. 165, foot- trobzcs must be taken to suggest that note) states that the ornamentation of they are unisexnal, particularly when the megaspores of S. sphenoplzylloides this is supported too by the indirect is distinctive and matches that of evidence supplied by JIctxocarpon ocdip- Zerndt7s type 14. Now the type 14 f ernurn. inegaspones of Zerndt are quite variable The fact that the microsp pore^'^ men- and surely comprise quite a group of tioned by Schimper (1870) are actual- species (cf. Zerndt 1940, p. 148). Nearly ly quite typical megaspores has been a,ll would be classed in the aplianozonate mentioned. The next suggestion of bi- section of Triletes, (Schopf, 1938). sexual cones of Sigillariostrobz~sis in a However, it does not seem that the paper by Kidston in 1897. In it he megaspores described by Miss LeClercq illustrates a specimen identified as Sigil- actually have their closest alliance with 7ariostrobzc-s sp. (op. cit. 1897, pl. 11, the type 14 megaspores of Zerndt or fig. 1) which lie thought might possess with the Aphunoxo~zati. The megaspore microsporangia as well as megasporan- she illustrates in proximal view on her gia. Only the megaspores are actually plate 11, figure 2, seems to have a demonstrated ; no microspores or con- typically folclecl lagenicnlate apex with clusive euiclence of microspores was ob- vestibule (cf. Schopf, 1938, p. 27). Al- tained from the purported microsporan- though a fern- of the spines on the ma- gia, and the size of imprints of the cerated spore on her plate IV, figure "microspores' ' are given as about 200 p. 10, are short and stont, this is probably In the absence of other definite charac- due to chemical attack since others ap- teristics, this seems too large for actual microspores. The fragmentary cone, in pear to be m-~~chlonger, more slender, any event, is inadequate as a source of and slightly sinuous, or curved. Miss definitive in£ormation. LeClercq indicates that the apiculae are all the same size (op. cit., p. 165) and Xiss LeClercq (1938) has recently as- also mentions that some of the spines signed a cone from the Yorli-ian in Eng- bifurcate, although she does not illus- land, f orlnerly identified mistalrenly as trate this feature. The megaspore coats Splze.~zoplzyllostachys, to Xigillariostro- bus splze~zoplzylloides n. sp. This cone are imperfectly macerated but fairly is undoubtecllg bisporangiate, as micro- translucent, judging from her photo- spores were isolated from the sporo- graphs taken by transmitted light. All phylls near the tip, and megaspores are these characters (with the exception of present throughout the basal part. It the bifurcate spines) are represented at is apparently sliglitly smaller than least partially in Triletes (Lay eniczda) Xaxoccwpo~zoedipter?zz~nz, and the sporo- kidstoni, in part,, as described and il- pliylls are alternately arranged in seem- lustrated by Zerndt (1934, p. 26-27 ; cf. ingly definite verticils, about ten per pl. 28, figs. 2 and 3; and 1937, pl. 16, figs. 1 and 8).I0 This also suggests an i7laaocccrpon slzorense ere bisexual, but alliance with Lepidostrobus rather than this was s~~pportedby no direct evi- TT-ithXigillariostrobus, since lageniculate dence. So far as the evidence goes, megaspores have their lmo~~mrelation- 8gain there is 110 apparent disparity ship with the former group. between Naxocarpon and Xigillariostro- Some of the microspores reported bus in regard to unisexnality of the from X. sphe~zophylloiclesare ex- cones produced. Eecorcls of microspo- ceptionally large (85 p) . Others, s~~p-rangiate cones of Xiyillariostrobzcs are posed to be immature, are about 35 p so largely inferential that this apparent in diameter. The former exceed those of agreement cannot be given ~~ndue Mazocarpow, in size b~tthe latter are weight at present. Nevertheless, it seems small enough to match those of Lepidos- most likely that unisexual microsporan- trobz~s. Conclusive information on the giate cones of Rigillnriostrobzls will be morpliology of the microspores might proved if an adequate study is uncter- be of considerable valne in iclentifyi~g taken. the genus, but apparently Miss Le- The cones of some Lower Carbonifer- C'lercq's material did not macerate very ous (Mississippian) sigillarians may well and the characters are not clearly have been typically bisex~~albecause defined on any of the microspores shown. the unisexual cones of Mazocarpolz must The sporophylls of 8. sphenoplzyl- he taken as quite highly specialized loides m7ere caducous as in several other and as derived from a more primitive species of Xigillariostrobus and in Maxo- condition. At some point in the sigillar- cnrpon shoremc. However this is of ian ancestry the cones must have been little or no diagnostic value because bisexual. Only a few species of modern cadncous isolated sporophylls of Ortho- Selnginellu (cf. Mitchell, 1910) attain lcplidostrobz~s (Arber 1922, p. 173) are similar specialization among the living at least as abundant as those of Sigil- lycopocls. Nel-ertheless, ~~nisexualcones lariostrobus, Maxocarpo~z, or other are quite in keeping with other features genera. of Pennsylvanian sigillarians which have For these various reasons it may be been mentioned, such as the pedunculate concluded that Sigillariostrobus spheno- mode of fructification, specialization of phylloides IlieClercq is not conclusively the gametophyte, characteristics of the identified as to genus and hence should megasporangium, etc., all of which ex- not be relied upon for evidence relating ceed the modern forms so far as relative to cones of Xiyillariostrobus. The cone structural modification is concerned. probably belongs to Lepidostrobus in- One of the strongest sources of evi- stead, and the occurrence of bisexuality dence indicating the alliance of Sigil- in it may not be as unique a feature as lariostrobz~sand ilfaxocnrpo??, is in the was s~~pposed.It is from beck of lower megaspores themselves. These are suf- Pennsylvanian age, and whether it is ficiently large and abundant in rSigil- particularly related to verticillate Lepi- lcwiostrohus cones to ha1.e been noted by dosfirob~cs of the Lower Carboniferous several observers. The megaspores in is not clear. general are those which the author has No other reports of bisexual cones of previously concluded must be classified Sigillariostrobzls are known to the au- together in the aphanozonate section of thor. It seems that there is little trnst- Triletes. This decision originally was worthy evidence that bisexual cones oc- based on a comparative study of spore curred in the sigillarian alliance, par- morphology. It was recognized that the ticularly during Pennsylvanian time. presence or absence of apiculae was a There is likewise no evidence of bi- character of importance only for spe- sexual cones occurring in Naxocarpo~. cific discrimination, and megaspores re- J'Iiss Benson assumed that cones of ported from cones of Xigillariostrobz~s strongly tend to confirm this view. In 10i\Iegaspores which are at least very closely most, descriptions of Xiyillariostrobus mlatcd to 11ri7etes (Lugen~icu7u) 7cidstoni Zerndt have been isolated from Cascyville coals of the species the spore characteristics are not Illinois basin and also from thin Mississippian coals in the upper part of the Chester series. f~~llyreported, and there is some ques- GROUP RELATIONSHIPS

tion as to the reliability of specific dif- since 1938 indicate their rarity or ab- ferences indicated by small-scale draw- sence from the greater part of the over- ings. Consequently these illustrations lying Mcleansboro. In lower Pennsyl- a,re of little value in systematic study vanian " Pottsville " beds, apiculate of the spores. On the other hand, by Aphanoxomxti are found more abun- working with both the isolated spores dantly, and the spines, which are the and the cones containing megaspores, chief means of differentiating species, more satisfactory conclusions have been are more prominent. Triletes nzamil- reached. All compression - preserved Znriz~s Bartlett is of this group and cones which are recognized as contain- also many of those spores which Zerndt ing aphanozonate megaspores have been (1934, pp. 17-18) has classified as type identified by various earlier authors as 14. These are all from beds of some Sigilluriostrobzis-not as the more com- degree of stratigraphic coincidence, pos- mon Lepidostrobus. This does not mean sibly falling in the lower and middle that all cones identified as Xigillariostro- Westphalian,ll (cf. text fig. 1 for ap- bus contained aphanozonate megaspores. proximate equivalence of stratigraphic The case of S. sphe.lzop1zli~lloideshas been terms). The horizon from which Naxo- discussed, and in several Sigillnriostro- curpnn shorense was derived belongs in bus species spores are not reported. lower Westphalian A. The megaspores It was not ~~ntilthe present study from this cone are also prominently was under way that it was realized that apiculate. From the illustrations given, the rnegaspores of Maxocurpo~z resem- one cannot tell m~~cliabout the type of bled characteristic members of the apha- ornamentation of M. shorense mega- nozonate section of Triletes (Schopf, spores because all are from sections. 1938). The megaspores of Jf. oedipter- One may hope that a f~d1description wunz can easily be dissolved from the of the English illuxocarpov, spores will coal-ball matrix by dilute hydrochloric be provided, as a good description is acid, and such spores display surface unavailable at present. In view of the characteristics somewhat better than the agreement in the forms obtained in sec- spores obtained from nitric acid macera- tions with those in sections from cones tion residues of coal. Arcuate ridges of of H. oediptermm, there can be no doubt these spores dissolvecl from coal-balls that the M. shoreme megaspores fall in appear soniewhat fainter than is usual the aphanozonate section of the genus For Triletes reinsclzi. Spores similar to (I'riletes along with megaspores of the these from M. oedipter?zzcnz but ob- type known from Sigillariostrobz~scili- tained by ordinary maceration of coal atus, S. rhornbibracteatus, S. cxarqtoc7cii, TI-OLI~~probably be difficult or impos- X. tieglzemi ( cf . illustrations in Kidston, sible to distiliguish from T. reimschi. 1897; Zeillel-, 1884, etc.) and the others There is no question as to their close which hmre been discussed. This agree- relationship with that species altlio~~gli ment, in the opinion of the writer, is nncertainty may exist as to their actnal one of the strongest yeasons for consid- identity. In a previous paper (Schopf ering Maxocarpon. and Sigillariostrobus 1938, p. 25) the probable relationship to be closely related. The number of of T. reinschi to several species as iden- megaspores in sporangia in the two tified on the basis of cone characteristics groups is not necessarily djscordant. was pointed o~~t.F'or example, spores They are not very numerous in spor- isolated from Sigillariostrobz~s cxar- angia of any species of Sigillariostrobus qzockii wonld probably also be referred although the numbers in individual to T. rei?zscJzi because the megaspore sporangia cannot be established with coats in both instances possess similar the same accuracy as in petrified ma- features. terial of iklaxocarpon. Apiculate members of Aphaqzoxomti It is evident from the preceding dis- (Triletes brevispiczdz~s) are only mod- cussion that biological criteria ciistin- erately abundant in certain benches of the Herrin (Mo. 6) coal bed in Illinois. I1Zerndt, 1040, p. 143, indicates that his type 14 spores extend through the Westphalian D, but Coal maceration studies continued are not found in the Ftephanian. SPECIFIC RELATIONSHIPS 33 guishing Sigillariostrobus from Maxo- but other information is lacking and a caTpoqa are notably absent. In large close relationship is dubious. Both of part, theref ore, the distinction between Lesquereuu 's species are recorded from the groups is probably artificial in that appreciably lower Pennsylvanian hori- the chief distinction is not based on zons. heritable characteristics but on differ- The Sigillariostrobus cone, designated ences in preservation which prohibit a as Lycopodites lacoei by Lesq~~ereux comparison of critical features. The (1884, p. 7801, is from Oliphant No. 1 demonstrable presence of intrasporan- bed in the anthracite field of Pennsyl- gial tissue in 1Waxocarpon is the only vania, of about middle Conemaugh age. outstanding criterion not known from It seems to be nearer to the age of the Sigdlariostrobus. Eochenski (1936 ) Calhoun horizon than other forms of mentions that the megaspores of S. cxar- Siyillar.iostrobzcs. The sporophylls of qaockii occasionally bear a faint reticu- (CLycopodites" Zacoei are longer than late imprint, This may be due to a those of i%laxocarpo~zoediptermtnz, ancl " ramental" remnant of intrasporangial more numerous sporophylls seem to be tissue as in the case of spores of M. oeclipler~zz~rn,(p. 17) and if so it is the present in each whorl. The spores are unlinown, but in Lesq~~ereux'drawing first record of such tissue from compres- (op. cit., pl. CVII, fig. 1) the sporangia sion fossils. If exact correlative rela- a,ppear relatively tumid and somewhat tionship is ever proved between these two genera, abundant evidence of this similar to those of J~U~OCCL~~O~I.How- ever close the generic affinity between sort m~~stbe sought. In the meantime Mazocarpon and SigiZluriostrobus may the basic information relating to the be, there seems no close specific rela- sigillarians seems to be more clearly in- tionship between M. oedipternum and dicated if the present grouping is main- species of either Maxocarpon or Sz'gil- tained. The likelihood is that these la.riostrobus, at least so far as the gen- genera could be merged for specimens of Pennsylvanian age without violating eral size and form of the sporophyll allows us to judge. any phylogenetic concepts. In the earlier history of the sigillarian alliance, niaxocctrpo~t shorense, on the other difficulties in interpretation are bo~ndl hand, appears to be more closely related to arise that will liingc on definition of to certain species of Sigillariostrobzts the genera. It will probably simplify than to either the older species, Maxo- the problems if nomenclature is applied carpon pettycurense, or to JI. oedipter- strictly, even though this results in the mrn. In length the $1. shoreme sporo- same biological group being generally phyll laminae seem to be about the same represented ~~ncierseveral generic terms as in Xigillariostrobz~s ciliatus Kidston, recognized as partially synonymons. 8.cxar~zockii Rochenski, and S. gothnni Bode. The latter two species are dis- SPECIFIC RELATTONSI-IIPS tinct from M. shoreme in that they both There are no available records of appear to have levigate iuegaspores, ancl Xiyillariostrobus in any beds adjacent also they are both geologically younger to the Calhoun horizon in Illinois. Cones than M. slzore!ase. The megaspores and of Maxocurpov, oedipternunz should be other details of Xigillariostrobz~s cilia- easily recognized in impressions or com- tus are in closer agreement with Jl. pressions by the unique character of slzoreme and they are probably rather lamina and dorsal heel of sporophylls, closely related. There is, of course, no and later investigation may disclose adequate basis for considering them them. Lepidophyllz~mbrevifolizinz Les- specifically identical. Sigillariost robus cpereux (1858) and the allied form, cxarvzockii and S. gothani appear closely L, nzimitif olium Lesquereux (1884), ap- related to each other although the in- pear to have similar very short laminae: formation available for S. gollzcmi is 34 GROUP RELATIOATSHIPX not entirely sati~factory.~Vhecone isolated spores of Triletes reinsc7zi. The peclniicle is notdemonstrable ancl the sporophylls are either verticillate or in distal tip of the cone is missing, How- a very low spiral. There is no character ever, judging from their imprint, the which conflicts with its identification as spores are clearly of the aphanozonate SiyiZZurz'ostrobz~s, altho~~ghimportant type and may also be represented among characters are not represented.

RELATION OF PALEOZOIC LYCOPOD GROTTPS Pennsylvanian sigillarians are a much There also are some highly specialized nio1.e specialized group than many of Forms frequently placed with the lepido- the coiitemporaneous lepicloclendrids. dendrids that are distinguished as the These two main groups of arboreous Lepidocarpaceae. Whether these spe- lycopocls surely had a common phyletic cialized forms actually belong in the source, and there has been a tendency lepidodendricl groups (typical repre- io conf~~sethe two groups, particularly sentatives of which are Lepidodefidron jn discussions of their f ructifications. and Lepidostrobus) or should be con- Consequently some discussion of certain sidered a separate group on a par with lepicloclendrid genera is pertinent here the lepiclodenclrids and sigillarians, need in order to bring out further the reasons not be given special consideration now; for considering them as distinct lineages it has been discussecl elsewhere (Sehopf, through Pennsylvanian and somewhat 1941) and the author is inclined to think later time. segregation will prove desirable. There One of the chief lepidodendrid groups is little reason to doubt that the bearing on this discussion is Lepidostro- lepidocarps (typically representecl by Lepidocurpov,, IlZiniocarpon, and pos- bus, a genus identified by characteristics (5) of its cones ancl tmoa large extent ap- sibly Lepidophloios) are more proximately correlative with Lepidoden- closely related to the lepidodendrids clron. Except for the large size attained than they are to the sigillarians or any by some species, ~epidos&ohusseems to other major lycopod gro-~lp.~~owever, have been the least specialized of the the specialization observed in Lepido- arboreous Paleozoic lycopocls through- carpon has been conf~~sedwith the clis- out the Carboniferous. Hesostrobus tinct type of specialization encountered Watson (1909) appears in the lower in Muxocarpo~z. Consequently it is Westphalian (Mountain 4-f t. mine, wortli while to point out these distinc- Clough foot, Dulesgate = Great Coal- tions in somewhat greater detail. ball horizon [?]) of England and may be rega~decl as a segregate from the main line of Lcpidostrobus. No great specialization is manifest and it is un- One source of confusion arises appar- likely that specimens of Hesostroho~s ciitly from a misunderstanding of the can be distinguished from Lepidostro- true morphologic nature of the iVnxo- bus, m+lien preserved as coalified com- curpon sporangiuni. Miss Eenson and! pressions. others since 1918 have frequently termed the Maxocnrpon female fructifications %ode (1928) indicates that only t11rce mega- " seed-like ". This terminology appears spores were borne "nalred" on each sl~orophvllof S. gotha?zi. The difficulty in distinguishing.' ron- ~~nacceptableaccording to the writer's tcnts of individual sporangia in compression ma- trrial niakes the uniform presence of three mega- interpretation of Muxocarpo?z oedipter- spores rionbtfnl. It is perhaps significant. bow- mnz. The prolonged association of spor- crcr, that they were at least no more numerous than in species $f Naxocarpon. Bode's suggestion opliytic tissue with Hazocarpo~mega- that the ;;pores lie nalred on thc bract" and that the sporangium is lacking, is too highlr anomalous 13The grouping of the lepidocarps with il1iade.s- to be accepted at its face value. 11e' citrs FEwn- mia under the name "L~pidospel-mae" (TIirmer ~inuitesCarruthers (1865) as a parallcl example. 1927) and assignment to ordinal rank by Zimtner- but it was shown long ago by Binncy (1871) ancl mann (1930) seems unwarranted. ilIiade.srnia has others that Carruthers' genus was bascd on a only the remotest possible relationship with an7 nlisconccption. of the arboreous forms. LEPIWBCARPON AND SPENCERITEL3 35 spores is the res~dtof lack of an effec- Scott pointed out that the integument tive mechanism for bursting open the of Lepidocnrpmz appears as a new organ sporangia, sl~clias is present, for ex- and cannot be interpreted as a mere up- ample, in Selaginellcc (BIitcliell, 1910). folding of the lateral wings of the pedi- Despite this, the essential f~ee-sporing cel. That this was a correct interpreta- adaptations are not materially altered tion is borne out by the study of Illiwio- in $lmocarpo~z. The tliiclcness of the carp0.n in which the integument is still megaspore coats indicates that the nutri- further elaborated and is entirely dis- tional bond between sporophyte and tinct from the sporophyll lamina. gametophyte was not any greater than Miss Benson further confused this in other free-sporing plants. The oc- issue ~vlienshe suggested (Benson, 1920) currence of intrasporangial tissue has that @cmtheZiophorzcs Bassler (1919) no essential bearing on the question was identical with Xigillcwiostrobzcs and since it has no effecti~econnection with compared favorably with Mc~xocarpo.n. the mature growth of the gametoplnytes. Eecent studies (Scliopf, 1940, 1941) in- The writer consiciers that the intiaaspor- dicate that Ca~ztheliophorus Eassler angial tissue served no essential protec- shows the seed megaspores and integu- tive or nutritive function after forrna- ments which characterize the genus tion of the spore coat. Any effect the Lepidocarpow, and, despite the cliffer- persistent intrasporangial tissue may elices in preservation, shodcl be identi- have had on spore distribution is that fied wit11 it. The relationship of Can- which mould result in any fr~e-sporing t?~clioph,orusand Sigilluriostrobz~sis en- plants with poorly ciehiscent sporangia. tirely indirect. There seenis to be no valid reason why these niegaspores or sporangia should The relationship between seed-bearing be termed "seed-like '. Such a desiena- hepiclocarpo~z and essentially free- tion merely confuses the useful clistlnc- sporing Maxocarpo~z can not be re- tion between free-sporing and seed- garded as direct. The two are more bearing plants. reasonably interpreted as divergent specialized reproductive types among the Carbonifero~~slycopods. Miss Benson's statement (1918, p. 582) that ((Maxo- On the other hand, the lepidocarps carpoyt is exactly intermediate between have every claim to recognition as true Lepidostrobz~s and Lepidocccrpon" is seeds because they possess all the phys- without basis either as an analogy or ical and physiological attributes of the homology since entirely diverse speciali- seed habit. The lepidocarp megaspor- zations distinguish the two groups. Both angium is indehiscent. The seed mega- were coexistent over a long period of spore is greatly enlarged, the megaspore geological time. LepicZocarpo?z wildia- membrane is modified for facile inter- k2zcm was described from the Calciferous change of food materials and has lost Sandstone of B-~~rntislandby Scott in its original essential function as a pro- 1901, and Walton (1936) has recently tective membrane just as much as in mentioned the occurrence of Lepido- any of the Paleozoic gymnosperniic seeds. ccirpo?~in beds of the Lower Carbonifer- The sporophytic structu~eis specialized ous Cementstone group from the Isle lo form a protective integument, and the of Arrali. It tlim at least equals and sporophyll lamina is probably effective may even antedate the existence of both as a dispersal mechanism. The distinc- iWaxocc~rpo~zand Sigillariostrobzcs. tive feature of Ncrxocarpon, viz. the ex- traordinary development of intrasporangial tissue (function ~~nlinown)is not characteristic of Lepidocarpon or of The reseniblance of Maxocurpoqz oedip- Lepidostrobus. The most distinctive fea- tcrwum and plants classified as Xpe~acer- t~~reof Lepidocarpon, the elaboration of ifrs is interesting chiefly because of the an effective integument, is not suggested obsc~~~ityof the affinities of Spemerites. by either Mnxocnrpon or Lepiclostrnbus. However, despite these similarities, there Although it has often been overlooked, is no proof of a direct relationship between the two groups, and until we trace of a ligule; in H. oedipternum have real evidence that Xpencerites is the presence of a ligule is hard to dem- either heterosporous or homosporous, onstrate although it has been found in s~~rmisesare not warranted. Scott, at a few instances. Although theoretical one time at least, entertained the pos- interpretation mould hold that the ligule sibility that- Spemerites imignis might of 144. oedipternzm is probably always have some sigillarian connection, al- present this is not proved, and the re- though no proof of this or any other ported absence of a ligule in Spencerites alliance has been f orthcoming.14 may also be because it is ephemeral and hard to find;15 (4) the sporophylls of The notable features of Spemerites Xpemerites may vary in arrangement which may be compared with flijlaxocar- from spiral to verticillate in the same 23017. are: (1) The cones in both genera manner as has been described for M. are pedunculate with the ped~~ncleof oedipternum (cf. Berricige, 1905, p. Spemerites bearing ' ' irreg~xlarbracts " 275). Such phyllotactic variability is somewhat as in M. oedipterm~nz;(2) the often present among modern lycopods, cone axis sometimes has a "pith" and consequently neither this similarity nor, sometimes is solid in inciividual species in fact, any of the others j~stmen- of both genera; (3) sporophylls of tioned, can be taken as necessarily sug- Spencerites have not yet shown any gestive of phyletic alliance.

CONCLUSION Jlaxocarpon oedipternum clearly indi- to a "sigillarian alliance" may hardly cates from its geological position that be questionect in its broader aspects, the the Maxocarpon type of sigillarian fruc- species nomenclature should remain es- tification existed at least throughout sentially the same; if anything the most of Pennsylvaliian time. D~~ring species should be more strictly defined. tliis period it seems unlikely that any The sigillarian alliance thus outlined sigillarian fructifications deviated very probably has little relationship in com- much from the Maxocarpon type, but mon with the lepidodendrids of the specimens preserved as compressions period despite similarities in many an- (Xiyillariostrobus) probably are not en- atomical details. Lepidocarpon shows tirely corgeneric although they may co- no close phyletic relationship to Maxo- incide for a considerable part of their carpon but instead represents a parallel respective geologic time ranges. Evi- line of specialization tracing back his- dence from several sources shows the torically as far as Maxocurpo?~itself. overlapping relationship of these gen- LepkZostrobus is a plant group, of lepi- eric groups, and similar types of evi- dodendrid alliance, which lacks the dence link them definitely with Sigil- sporangial elaboration shown in differ- laria. However, as frequently is the ent ways by Lepidocarpouz and Muzo- case for fossil plant material, conclusive carpon. Lepidostrobus is present in the evidence is lacking for species. Thus, al- American uppermost Devonian, accord- though the assignment of these genera ing to Read and Campbell (1939)) and 14The discussion of the relationship of Spevzcer- thus is the most ancient representative ites and other forms given by Watson in 1909 of the groups mentioned. Probably the does not accord with historical facts as known at present. For example, Lepidostrobus kentucky- two specialized lines originated from ensis Scott and Jeffrey is from the uppermost Devonian, according to recent studies by C. R. this unspecialized (but geologically per- Read (Read and Campbell 1939). Evidently sistent) lepidostrobid stock early in therefore, Lepidostrobus candot be regarded as a derivative of the much younger forms of Spen- Mississippian time, although it may cer4te.s and J!le.sostrobus from beds equivalent to the lower Pennsylvanian in age. If there is any have been still earlier. Considerable direct phyletic conllection the sequence must be interest attaches to definition of the reversed from that which Watson suggested. Lepi- dost~obus shows no characters indicative of a specialized groups in the Mississippian highly advanced type but represents chiefly en- in view of their probable phyletic deri- largement of a primitive h~terosporous type of cone. The writer considers it less adranced than the relatively primitive but modern genus Selag- actually very few specimens of Spencerites inella. cones have been studied. vation in this time interval. cones should help in further indicating During Pennsylvanian time these ly- the sigillarian evolutionary sequence as copod alliances apparently were dis- well as in serving directly stratigraphic tinct. It appears from the present study purposes. As these spores are obtain- that Pennsylvanian fossils of lepidoden- able from coal, they also will aid in drid alliance need not be confused with evaluating the importance of sigillarians sigillarian types in phyletic considera- in coal formation. T~LIS,the greater tion. If a precise evolutionary sequence abundance of the aphanozonate species of sigillarian fossils (or any others for Triletes reinschi and Triletes brevispicu- that matter) can be established in detail lus in the Herrin (No. 6) coal (Schopf, these fossils will become much more 1938, pp. 27, 29) in the coal bench im- usef~das stratigraphic indices, and fur- mediately overlying the blue-band clay ther investigation along this line is con- parting is one of the factors to be con- templated. sidered in explaining the origin of this Aphanozonate megaspores seem defin- type of coal. F-~~rthermorethe im- itely linked with the sigillarians. In a portance of the sigillarians as plants general w,ay it seems that apiculate capable of establishing themselves on species of Aphanoxonati represent char- what must have been a dense clay sub- acteristic sigillarians in the Lower stratum (the blue-band) must be recog- Pennsylvanian rocks, whereas levigate nized. These aphanozonate spores are Aplzunoxolzati are more abundant in the by no means alone in this portion of the Upper Pennsylvanian. Detailed studies coal bed but, in marked contrast to of these species based on isolated spores some of the other species present, they and spores associated with sigillarian are definitely more abundant there. REFERENCES

REFERENCES

ABSOLON,R. G., Lower Carboniferous coal- CADY,G. H., The occurrence of coal-balls in ball flora of Haltwhistle, Northumber- No. 6 coal bed at Nashville, Illinois: land: Proc. Univ. Durham Phil. Soc., Trans. Illinois Acad. Sci., vol. 29, pp. VOI. 8, pp. 73-87, 1929. 157-158, 1936. ALLEN, D. A., The igneous geology of the CADY,G. H., The Illinois Coal Field; in, Anal- Burntisland District: Trans. Roy. Soc. yses of Illinois coals: U. S. Bur. Mines Edinburgh, vol. 53, pp. 479-501, 1924. Technical paper, in press, 1941. ARBER,E. A. N., Critical studies of Coal- CALDER,MARY, Notes on the Kidston collec- Measure plant-impressions : Jour. Linn. tion of fossil plant slides, 111-Anatomy Soc. London, Botany, vol. 46, pp. 171-217, of RiyiZZuria eZeyans Brong.: Trans. Roy. 1922. Soc. Edinburgh, vol. 58, pp. 49-54, 1934. BASSLER,H., A sporangiophoric Lepidoplzyte CARRUTHERS,Mr., On an undescribed cone from the Carboniferous: Bot. Gaz., vol. from the Carboniferous beds of Airdrie, 68 (21, pp. 73-108, 1919. Lanarkshire: The Geol. Mag., vol. 2 BESSON,M., The sporaagiophore-a unit of (16), pp. 433-440, Oct. 1865. structure in the Pteridophyta: New C~RDA,A. J., Flora Protogaea: Beitriige zur Phyt., vol. 7, pp. 143-149, 1908. Flora der Vorwelt, 2nd ed., Berlin, 1867. BENSON,M., Maxocarpon, or the structure of CROOKALL,R., The plant "break" in the Car- SigiZZariostrobus: Ann. Bot., vol. 32, pp. 569-589, 1918. boniferous rocks of Great Britain: Bull. of the Geol. Survey of Great Britain, BENSOK,M., CantheZiopho~us,Bassler : New NO. 1, pp. 13-26, 1939. records of SigiZlariostrobus (Muxocur- pon): Ann. Bot., vol. 34, pp. 135-137, DARRAH,W. C., Fossil flora of Iowa coal- 1920. balls: Bot. Museum Leaflets, Harvard BERRIDGE,E. M., On two new specimens of Univ., vol. 7 (8), pp. 125-136, 1939. Spencerites insignis : Ann. Bot., vol. 19, DIX, E., The succession of fossil plants in the pp. 273-279, 1905. South Wales coal field with special refer- BERTRAND,PAUL, Les Flores HouillBres ence to the existence of the Stephanian: d'Amerique d'Apres Les Travaux de M. 2nd Cong. Carb. Strat., Heerlen, 1935, David White: Ann de la Soc. GBol. Du vol. 1, pp. 159-184, 1937. Nord, vol. 58, pp. 231-254, 1933. FELICIANO,J. M., The relation of concretions BERTRAND,PAUL, Nouvelles correlations to coal seams: Jour. Geology, vol. 32, stratigraphiques entre le Carbonifere, des pl3. 230-239, 1924. Btat-Uiiis et celui de 1'Europe occi- FISHER,M. C., and NoB, A. C., A list of Coal- dentale d'apres Jongmans et Gothan: ball plants from Calhoun, Richland Ann. de la Soc. Geol. Du Nord, vol. 60, County: Trans. Illinois Acad. Sci., pp. 1-16, 1935. (1938), vol. 31, pp. 178-181, April, 1939. BISNEY, E. W., Observations on the struc- GORDO~V,W. T., On the nature am1 occurrence ture sf fossil plants found in the Car- of the plant-bearing rocks at Pettycur, boniferous Strata; Part 11, Lepidostro- Fife: Trans. Geol. Soc. Edinburgh, vol. bus and some allied cones: Paleonto- 9, pp. 353-360, 1909. graphical Society, London, vol. 24, pp. 33-62, 1871. (Also published, together GRAHAM,ROY. Pennsylvanian flora of Illi- with others of the "Observations" series nois as revealed in coal-balls, 11: Bot. by Binney, in a separate volume.) Gaz., vol. 97, pp. 156-168, Sept. 1935. BOCHENSKI,TADEUSZ, Uber Sporophyllstande GGOGAX,R. 3%.and LAMAR.J. E., Agricultural (Bliiten) einiger Lepidophyten aus dem limestone resources of Cumberland, Produktiven ICarbon Polens : Ann. de Effingham, Clay, Richland and Jasper la Soc. Geol. de Pologne, Tome 12, pp. Counties, Illinois. Illinois Geol. Survey 193-240, Annee, 1936. Rept. Inv. No. 65, pp. 1-44, 1940. BODE,H., Ein Neuer Sigillarienzapfen : Sigik HAGI~E,Ph. Note sur le Structure d'uae Zuriostrobus gothani, n. sp.: Jahrb. d. Xigillaria camelee du terrain houiller Preuss. Geol. Lanclensanstalt, Bd. 49, inferieur de Lancashire: Ann. Soc. Geol. Teil I, pp. 239-244, 1928. du Nord, vol. 50, pp. 110-115, 1926. REFERENCES

HEERLESCOXGXESS COAIPTE RENDU; CongrGs KUBART,B., Pflanzenversteinungen enthalt- pour l'avancement des Etudes de Strati- ende Knollen aus dem Ostrau-Karwiner graphie CarbonifBre, Heerlen, 7-11 Juin Kohlenbecken: Sitzungsber. d. K. Akad. 1927, Liege, 1928. Deuxieme CongrGs d. Wiss. in Wien, Math.-Naturw. Klasse, pour I'avancement des Etudes de Strati- Bd. 117, pp. 573-578, 1908. graphie Carbonifitre, Heerlen, Sept. 1935, 3 vols., Maestricht, 1937-1938. KVBART,B., Corda's Sphaerosiderite aus den1 Steinkohlenbecken Radnitz-Braz in Boh- HIRMER, M., Handbuch der Palaobotanik, men: Sitzungber. d. K. Akad. d. Wiss. Band 1: R. Oldenbourg, Munchen und in Wien, Math.-Naturw. Klasse, Bd. 120, Berlin, 1927. pp. 1035-1048, 1911. HIRMER.M., Uber Vorkommen und Verbrei- KUBART.B., Uber die Cycadofilicineen Heter- tug der Dolomitknollen und deren angium und Lyginodendron aus dem Flora: 1st Cong. Carb. Strat., Heerlen, Ostrauer Kohlenbecken : Osterreichische 1927, PP. 289-312, 1928. Bot. Zeitschrift, Jahrg. 64, pp. 8-19, 1914. HIRI~E~.M., Der Fossilinhalt der Dolomit- LAXG,W. H., Preliminary statement on the knollen der Westdeutschen Paralischen morphology of the cone of Lz~copocliulnz Kohlenbecken: pp. 154-158, in Kukuk, cernuunz and its bearing on the affin- P., Geol. d. Niederrheinisch - Westfal- ities of Xpencerites: Proc. Roy. Soc. ischen Steinkohlengebietes, Berlin, 1938. Edinburgh, vol. 28, pp. 356-367, 1908. HIRMER.MAX, Die Pflanzen des Karbon und LECLERCQ,S., Les Coal-Balls de la Couche Perm und ihre Stratigraphische Bedeut- Bouxharmant des Charbonages de Wer- ung. Teil 11: Die oberkarbon-F'loren der ister: Mem. de la Soc. Geol. de Belgique, Paralischen Becken des Westlichen pp. 1-79, Liege, 1925. Mittel-Europa. Abschnitt 1: Paleonto- graphica, vol. 84, abt. B, pp. 1<3-1619, 1940. LECLERCQ,S., Sur un 8igiZluriostrobus h&&- ospor8 : Xigillnriostrobus sphenophyl- Hos~

READ, C. B., and CAMPBELL,GUY, Prelimi- Soc. Edinburgh, vol. 58, (2), pp. 313-338, nary account of the New Albany shale 1935. flora: Amer. Midland Nat., vol. 21, pp. WANLESS,EI. R., Pennsylvanian correlations 435-453, 1939. in the Eastern Interior and Appalachian REED,F. D., Structure of some Carboniferous coal fields: Geol. Soc. Am. Spec. Papers, seeds from American coal fields: Bot. NO. 17, pp. 1-130, 1939. Gaz., vol. 100, (4), pp. 769-787, June 1939. WATSON,D. M. S., On Mesostrobus, a new SCHI~P~,W. Ph., Traite de Paleontologic genus of Lycopodiaceous cones from the Vegetale, vol. 2, Paris, 1870-1872. Lower Coal Measures, with a note on SCHOPF,J. M., A significant collection of the systematic position of Xpencerites: American coal-balls : Chronica Botanica, Ann. Bot., vol. 23, pp. 379-397, 1909. vol. 4, pp. 384-385, Sept. 1938, a. WATSON,D. M. S., On the structure and SCIIOPF, J. M., Spores from the Herrin (No. origin of the Ulodendron scar. Ann. Bot. 6) coal bed in Illinois: Illinois Geol. 28, 481-498, 1914. Survey Rept. Inv. No. 50, pp. 1-73, WELLER,J. MARVIN,Geology and oil possi- 1938, b. bilities of extreme southern Illinois : SCHOPF,J. M., Two new Lycopod seeds from Illinois Geol. Survey, Rept. Inv. No. 71, the Illinois Pennsylvanian: Trans. Illi- pp. 1-71, 1941. nois Acad. Sci., vol. 30, pp. 139-146, WHITE, DAVID,Environmental conditions of 1938, c.; Illinois Geol. Survey Cir. 28, deposition of coal: Trans. Amer. Insti- 1938 c. tute of Mining and Met. Engineers, vol. SCITOPF,J. M., LepicZocarpon: in Janssen, 71, pp. 3-23, 1925. Ray, Some fossil plant types from Illi- ZAI,E~SSI

All specimens illustrated are in the collections of the Illinois State Geological Survey at Urbana. Relative magnification of the figures is accurately given by linear scales adjacent to each or as noted in description of the fi,awes. PLATE 1.-MAZOCARPON OEDIPTERNUM forrna MEGALOPHORUM

FIG. 1. Part of a nearly radial section of cone: From C. B. 136 (20). 2. Part of a nearly radial section of cone including median section of normal sporophyll (N Sp) . From C. B. 136 (20). 3. Tangential section of cone suggesting a low spiral arrangement of sporophylls: From C. B. 136 (9). 4. Tangential section of cone transecting sporangia toward the distal end and showing lateral keels of sporangia (SpK) inclined downward: From C. B. 136 (3).

PLATE 2.-Mazocarpon oedipternum forma Megalophoruin

Photograph showing connection between the cellular "ramentum" (R) on concave proximal surface of megaspore and the intrasporangial tissue: From C. B. 136 (18). Nearly radial thin-section through cone. Compare with text fig. 5b: From C. B. 136 (24). Section across distal end of more or less fragmented sporangium, transecting the apical prominence of the most distal megaspore. A greater thickness of the sporangial keel (SpK) is cut in this plane. The tissue of the keel is well shown: From C. B. 136 (34). Transverse section of sporophyll (tangential to cone axis) taken near the proximal end of the sporangium. Thin areas (T) in the prismatic outer layer of the sporangium may be seen. Central tissue is well shown; cells are much larger than those in the sporangial keel (compare with fig. 3) : From C. B. 136 (20). 5a, b, c. Megaspores of Maxocarpon oeclipter?zwm [corresponding to Triletes reinschi (pars.) 1 isolated by solution of calcite coal-ball matrix. In some areas "ramentum" has scaled off. Spore photos by E. A. Platt. PLATE 3;--Female Gametophy tes of MAZOCARPONOEDIPTERNUM

FIG. 1. Small isolated globule of tissue observed in chamber of gametophyte at apex of spore; illustrated at lower magnification on plate 2, figure 3: From C. B. 136 (34). 2. Small isolated globule of tissue (8-12 cells) in chamber of gametophytic tissue at apex of megaspore: From 130 C2 (5'). 3. Gametophytic chamber (fig. 2) shown in relation to the rest of the spore at lower magnification (same as for figs. 5, 6, and 7). The chamber is at the spore apex; except in this area the megaspore cavity is filled by crystalline calcite devoid of tissue. Spore coat appears thicker than normal because it is cut obliquely: From 130 C2 (5). 4. Sections of two megaspores oriented at right angles to one another. An archegonium, also shown on plate 4, figure 5 (A), surrounded by very delicate gametophytic tissue, is seen (cut transversely) in the spore at the top. The spore below shows shrunken endosporal membrane: Fro;m C. B. 116 A 3b, (T6). 5, 6, 7. Three successive longitudinal sections of a megaspore with delicate gametophytic tissue and apical archegonium. Figure 5 is median and shows neck of archegonium protruding slightly into apical vestibule. Figures 6 and 7 are at more tangential levels respectively. A dark humic mass occupies the neck and top of the venter: Sections at same magnification, from C. B. 116 A3 (T3) and 116 A3b (T4) and (T5) respectively. 8. Transverse section of apex of megaspore showing trilete rays and section through top of archegonium: From C. B. 130 B. 9. Archegonium (fig. 8) at higher magnification. A red hurnic globule occurs in the center of archegonium which is filled with more dispersed flocculent humic material.

PLATE 4.-~~ZOCIIRPONOEDIPTERNUM

FIG. 1. Section of portions of somewhat fragmented sporophylls cut tangential to cone axis and containing megaspores with gametophytes. la. Megaspore with gametophyte and archegonium from same section as fig. 1. Compare with plate 3, figs. 5, 6, 7: From C. B. 116 A3b (T5). Megaspore with fusainized gametophytic tissue. Archegonium at apex cut tangentially: From C. B. 116 A3b (T3). Transverse section of sporophylls (tangential to cone axis) proximal to great expansion of dorsal heel, (DH). Sporangium on left appears to have only one lateral sporangial keel (SpK), the other having been eliminated due to crowding: From C. B. 136. Megaspore with partially fusainizecl gametophyte shrunken away from distal spore wall. A small tangential slice of the archegonial venter is shown: From C. B. 116 A3b (T5). Archegonium, same as shown near center, fig. 1, at higher magnification. Delicate gametophytic tissue and some cells of venter can be seen: From C. B. 116 A3b (T6). Proximal section of microsporangium adjacent to cone axis. Sec- tion from two planes as in plate 5, figs. 1 and 3; sporangial attachment and collapsed T-shaped vestige of subarchesporial pad (s) is shown: From C. B. 124 E (T34). Median longitudinal section passing through dorsal loop (DL) of sporophyll trace in 'M. oedipternunz f. micropho?-utm. Scalariform "transfusion" type tracheids occur inside the loop. A shrunken remnant of the ligule (Lig.) is shown above the downturn of the loop: From C. B. 124 E (32). Distal end of same sporophyll from which fig. 7 was taken, showing relation of sporophyll trace to sporangium, etc. Compare with text fig. 3b. PLATE 5.-MAZOCARPONOEDIPTERNUM

Forma ~nicrophoru~n,;slightly oblique longitudinal (near-radial) and transverse sections at the tip of a cone, obtained simultaneously on a single peel. Ruled white line indicates juncture oC the two planes of section: From C. B. 124 E (T38). F'orma ~neyaZopho?-unx;transverse section for comparison with similar sections of f. ~nicr-ophorumin figs. 1 and 3: From C. B. 136. Forma microphorum; section taken in the same manner as that shown in fig. 1 but through the basal part of a different cone. Longitudinal section is tangential. Sterile sporophylls are shown at the cone base. Stele has disintegrated and is absent in the oblique t.ransverse part of the section: From C. B. 124 E (T38). 4a. Microspores showing papillate surpace of exospore. 4b. Exospore more or less torn off, exposing the endospore which is shown carrying the trilete sutures. A thickened darker spot is shown at the tip of each pyramic segment of the endospore. Spore photos by E. A. Platt. 5. Section at higher magnification taken slightly tangential to microsporangiate cone apex. Vascular traces (v) extend into undevel- oped sporophylls at cone tip. Strict verticillate arrangement is evident: From C. B. 124 E (T32). 6. Forma 1neyulop7zoru1n; tangential section of cone shown in fig. 2 adjacent to the plane shown on a slant at the left of that figure. Sporophylls are apparently in verticills: From C. B. 136.

PLATE 6.-Penduncle and Vascular Structure of MAZOCARPONOEDIPTERNUM

FIG. 1. Transverse section of peduncular stele with isolated tracheid groups in medullary area: From C. B. 136 A. 2. Transverse section of peduncle showing bract bases (with large parichnoidal cavities) in spiral arrangement. Inner cortex not preserved: From C. B. 195 D (TI). Transverse section of stele in cone axis essentially lacking pro- senchymatous medulla. Stele is slightly larger than those shown in figs. 4 and 10 (compare magnification scales): From C. B. 139. Transverse section of stele in cone axis showing relatively large thickness of metaxylem and small medullary area with scattered central tracheids: From C. B. 130 B. Extreme tangential section of stele showing spiral elements in sporophyll trace and on the outside of the adjacent stele. A few scalariform elements also are entering the trace: From C. B. 136 (18). Longitudinal section of stele in megasporangiate cone axis showing prosenchyniatous medullary cells, scalariform metaxylem, and annular and spiral protoxylem tracheids : From C. B. 136 (21). Horizontal portion of trace from sporophyll pedicel consisting chiefly od scalariform tracheids: From C. B. 136 (18). Sporophyll trace ascending from the stele in cone axis showing spiral, annular, and scalariform tracheids: From C. B. 136 (18). Longitudinal section of stele also shown in fig. 10 (cf. also plate 5, fig. 1) showing annular medullary tracheids, scalariform metaxylem tracheids and outgoing sporophyll traces: Fkom C. B. 124 E (T34). Transverse section of stele in cone axis (cf. plate 5, fig. 1) showing verticillate arrangement of outgoing sporophyll traces. Isolated medullary tracheids are present: From C. B. 124 E (T34).