THE DISTRIBUTIOi-J OF DENSOSPORES

?lIAVIS A. BUTTERWORTH* Department of Geo1c'gy, University of SIH'ffleld, United Kingdom

ABSTRACT by Butter.worth et aZ. (1964a), and by Staplin Densospores include species of the miospore & Jansonms (1064). These workers divide genera Cingulizonafes (Dybova & Jachowicz), the group into [our genera: Densosporites Crisfafisporifes (Potoni6 & Kremp), De1/sosporifes (Berry) Butterworth, J ansonius, Smith & (Berry) and Radiizonafes Staplin & Jansonius Starlin, in which the cingulum is massive from the literature of Europe and ~orth America, and the exine without prominent ornament; and ElIryzol1ot1'ilefrs i'aumoya, Hymellozonofrilefes Naumova and Tremafo:;onotrilefes Kaumova from Cristatisporitfs (Potonie & Kremp) Butter• the Russian literature. An account is given of \\'orth, Jansonius, Smith & Staplin, the taxonomic position of densospores and of their in 'I hich the cingulum and whole of the morphographic variation in clifferent parts of the column. distal surface are covered with rows or Densosporcs have been recorded in large numbers, cristae of verrucae or spines; Cingl{Zizonates mainly from coal seams, from the Devonian to the (Dybova & J achowicz) Butterworth, J an• Permian of the northern hemisphere. The geo• son ius, Smith & StapJin, in which the graphical distribution of these occurrences forms the subject mattcr of the present paper. Tn general cingnlum is prominc:ntly divided into an densospores first occur in abundance in more inner thick and an outer thin part; and northerly regions and are displaced gradually Radiizonates Staplin & Jansonins in \\'hich southwards during the Carboniferous. They are the divi~ion of the cingulum into thicker most common and have the longest ranges, in areas of slow subsidence. and thinner parts is accompanied by radial striations. These [our genera are included INTRODUCTION by Smith & Butten\'orth (in press) in a new infraturnla - Cingulicavati, described to include trilete cavate spores with simple or THEmiosporesdensosporescharacterizedare a bygroupa thickof ridged laesurae and a comprehensive equa• cingulum or equatorial girdle \\'hich torial thickening (cingulum) or extension may be massive or variously differentiated (zona) of the outer exine layer. Densospo• into thinner and thicker part". These rites and Cristatisporites \\ ere previcusly spores are distinguished from more simple assigned to the infraturma Cingulati Potonie cingulate forms by the two-layered nature & Klaus along with cingulate genera in which of the exine, the intexinc forming the inner the exine is not two-layered, \-"hilst C1'ng1tli• body and the exoexine being expanded zonates and Radiizonates were assigned to equatorially to form the cingulum (BHARAD• the infraturma Cingulizonati Dybova & WA}, 1958; SMITH, 1960; HUGHES, DETT• J achowicz; both infratnrma "'ere designated MANN & PLAYFORD, 1962). The group is for acavate, zonate spores. essentially Carboniferous in age but has also In the U.S.S.R. the species of the group been recorded from the Devonian and the are variously. assignerl among the followiJ]g Permian; it is restricted in occurrence to genera: EuryzollotriZetes Naumova, 1937, the northern hemisphere. with a massive cingulum; Hymenozonotri• The botanical affinities of the densospore letes Naumova, 1937, with a differentiated group are still somewhat obscure, (the cingulum; and Tre11latozonotrilfies Naumova, relevant findings are summarized in BUT• 1937 with an alveolate or punctate cingulum. TERWORTHet aZ., 1964a), hut Chaloner (1958, Luber & Waltz 119+1) include all spores of 1962) and Bharadwaj (1958) have isolated the group in the comprehensive genus various species from the cones of herbace• ZOllotn'Zetes Waltz, 1935 which Potonie & ous lycopsids. K remp (1954) use at subturma level. Very many species of densospores have Ishchenko (1956, 1958) assigns species wi th a been described and they have been sub• massive cingulum to Euryzonotriletes and divided at the generic If'vel in various ways. others, including forms else\vhere assign• Their taxonomic position as applied in ed to Cristatisporites and Cingulizonates, Europe and North America is summarized to HYl1lfnOZol1otriZetes; one 5pecies only is

*Present acldress: College of ;\cl\'anced Technology, Bosta breen, Birmingham 4, U.K. 16 BUTTERWORTH - THE DISTRIBUTIOX OF DEKSOSPORES 17

assignerl to Trematozonotriletes _. T. variabilis enough peat had accllmulatrd above the (\Valtz) Ishchenko, with a markedly al\-co• general ground water level. This theory late cingulum. was borne out by Butterworth (1964) who showed that D, sphaerotriallgularis, and THE OCCURRENCE OF DENSOSPORES hence Cl assidurain, is particularly abundant The association of certain densospores in the thick seams which occur towards the with llull coal \ras fIrst noted by Thiessrn stable margins of basins of coal deposition. (1930) and ,,'as confirmed by other ,,'orkers. The prevalence of Iycospores in the more Smith (1957, 1962, 1964) has shmm that in expanded part of the sequence occurring the Upper Westphalian A and Westphalian nearer to the cen tres of basins of deposition B, Densosporites sphacrotriangularis Kosanke, was demonstrated by this author in the characterising his Densospcre PhasE', coalfielns of Central England and by Hac• occurs almost exclusively in bands of cras• quebard & Donaldson (1964) in the Sydney sidnrain, towards the middle and top of Coalfield of Nova Scotia. coal seams. Smith (1962) suggested that the The stratigraphical occurrences of spores peat forming crassidurain was deposited of the densospore group, which are detailed under at IE'ast partly aerobic conditions, in the follo\\'ing sections,' are summarized and that it could have been formed wherever in Text-fig, 1.

..•.v>'";n'v> ...... •. '"..•. "ijP>::l"'":or~'0;:JCbv>E)...... ,;:r....:or ;:r::l 0> Cb"s.P>Ul::l'\J P> 0 ::l Cb::l t:I "ijzZ9~f;;f;;'::l0e:.:;::td...,f;;.t:IS::lS f;;' 0> <: P> .g>- >- f;;'Cb ::l q~ f;;' n

000000000 Kaiping 000000000000000000000000000000000000000 Tunguska xxxxxxx SpitslJergern xxxxxxx Moscow xxxxxxxxxxxxxxXOOOOOOOOOOOOOO Dnieper -Donetz xxxxxxxxxxxxxxxxxxxxxxxxxx Bug xxxxxxxxxxxxxxxxxxxx Upper Silesia xxxxxxxxxxxxxxxxxxxx Turkey xxxxxxxxxx xxxx xxxx Spain xxxxx xxx North Africa xxxXOOOOOO Saar and Lorraine xxx Plzen xxxx pfalz xxOOOO French limnic xxxxxxxxxOOOO Ruhr xxxxxxxxx Campine xxx Mons xxx Pas de Calais xxxxx xxxxxxxxxxxxxxxxxxXOOoxxx Britain xxxxxxxxxxxxxxxxxxOOO Eastern Canada xxxxxxxxxxxxxxxXOOOOoxx l.:nited States xxxx N.\V. Canada

TEXT-FIG, 1 - The distribution of densospores in coal basins from which miospore assemblages have been described. (Crosses denote miospore assemblages in which densospores are present, noughts miospore assemblages in which densospores have not been recorded.) 18 'tHE PALAEOBOTANIST

1. Devonian in the Lovyer Carboniferous are zonate, and of these 60 per cent to 70 per cent are Richardson (1960, 1965) has described thickly fringed, that is have a cingulum. several densospore species from the Middle Of the seven predominant spores listed Old Red Sandstone of north-fast Scotland; Z(lnotriletes crassiptertts Waltz (l.e., PL. 5, although the differentiation of the exim FIG. 64) is a typical Densospr,rites form with into two layers has not been demonstrated a massive cingulum, Zonotriletcs dentatus in these species, they appear to have the Waltz (t. C., PL. 7, FIG. 103) has a cingulum same internal organisation as their Carboni• modified by the presence of small cones and ferous equivalents; they differ fro m Carbo• Z. variablilis (l. C., PL. 5, FIGS. 65, 66) has niferous species in their much gr eater size a punctate cingulum. In the Tunguska (87 to 159 microns, compared wi th 25 to Floral Area, to the south and east, spores 110 microns in the Carboniferous). Two with 'thick massive fringes' are stated to of the species, Densosporites del/on/eus be completely lacking. Richardson and D. oreadensis Richardson, The rather more detailed assemblages which have the characteristic bizonate given by Ishchenko (1958, FIGS. 1-11) for cingulum of Cingulizonates, are orramented sequences in the Dnieper-Donetz Ba:o-in with small bifurcating spines such as occur show that whereas Hymenozonotriletes bialatus on many Devonian spores. The three (Waltz) Ishchenko, a spore with a bizonate species of Cristatisporites describen differ cingulum, and Tre11latozonotriletes var'iablilis from younger species only in their greater (Waltz) Ishchenko are hath common at size. Similar forms have been described some horizons in the Tournaisian they are by Luber & Waltz (1941) hom the Timan more dcminan t in the Visean, where in Peninsular and the Kuznetsk Basin, and bv addition H. cOlllmutatus (Waltz) Ishchenko, Naumova (1953) from the Upper Givetia~ with a bizonate cingulum, and Euryzonotri• of the Russian Platform. letes crassipterus (Waltz) Ishchenko are McGregor (1960) has described a denso• also common. spore, D. erassus, vyith a massive cingulum Jackowicz (1964, PL. 2) records low and of large size, from a coal of Givetian age numbers of Densosporites from the Tournai• in the Canadian Arctic. Since only three sian of the Bug Basin of Eastrrn Poland; specimens of the spore were found this occur• this genus is more common in the Visean rence is perhaps not important; more signi• where species of C1:ngulizonates are also ficant is the record in this Seam of 33 per present. cent of ThoUsporites Butterworth & Wil• Several of the coals and shales examined liams, a genus differing from those of Lhe by Playford (1962, 1963a) from the Lower denso::>pore group only in the extension of Carboniferous of Spitsbergen contain high the equatorial thickening over the distal numbers of densospores. In this author's polar area, and described originally from the Tournaisian material (PLAYFORD, 1963a, Namurian A. TABLE I, p. 661) the coal sample G1091 In Richardson et at. (1964, TEXT-FIG. 1) contains 36 per cent Densosporites dentatus Dens(lsporites is recorded by Taugourdeau• (Waltz) Potonie & Kremp and smaller Lantz from the Frasnian of France and by percentages of D. spitsbergensis Playford Peniguel from the Givetian of North Africa. [D. regalis (Bharadwaj & Venkatachala) No details of abundance or speciation are Smith & Butterworth] and D. diatret1/s given in this paper. Playford, forms with verrucose and spinose ornament of the cingulum, and D. vario• 2. Tournaisian and Visean margillat1ts Playford, which has an irregu• larly thickened cingulum and a characteristic The largest amount of data on Lower undulating equatorial ontline. Several of Carboniferous spore assemblage is that the assemblages from other sediments from the U.S.S.R. Luber & Waltz (1941, contain over 20 per rent of densospores, pp. 7, 8 of the Humble Oil and Refining the most commonly o,cllrring forms being Company's typescript of the Canadian D. dentatus, D. diatretus and D. variomargi• Geological Survey's translation) state that natus. The Visean material examined also in their Westphalian Floral Area, that is in contained a coal rich in densoc;pcres (l.c., areas adjoining the Urals, 72 per cent to TABLE 2, p. 662, sample G 1092) in which 75 per cent of the total spores encountered the dominant species are D. variabilis and BUTTERWORTH - THE DlSl'RIBUTION Olc DENSOSl:'ORES 19

D. regalis; these species, along with D. of which were forms with a bizonate cingu• bialatus and D. dentatus are sometimes also lum and some evidence of radial plications abundant in the associated sediments. (l. e .. , PL. 4, FIGS. 11-14). A similar assem• Bharadwaj & Venkatachala (1961, p. 40) blage, in which Cing1tlizonates bialatus was record 2·4 per cent of Densosporites and the second most abundant spore encoun• 60·8 per cent of Cristatisporites in a Lower tered, has been described by Playford & Carboniferous shale from Spitsbergen; their Barss (1963) from Axel Heiberg Island in in terpretation of Cristalisporites is some• the Canaclian Arctic. These authors state what broach'r than that used here and in• (l.e., p. 4) that a comparable assemblage cludes species which the pre~pnt aut.hor occurred in a sample examined from Elles• would assign to Densosporites. mere Island, also in the Canadian Arctic. Sullivan (1964a & b) has described Tournaisian and Visean assemblages from 3. Namurian the Forest of Dean in Britain; no denso• spores occurred in the former, but in the Records of densospores in rocks of Middle latter Densosporites (A nulatisporites) anu• and Upper Carboniferous age in the U.S.S.R. latus (Loose) Schopf, Wilson & Bentall, are scant. Luber & Waltz (1941) state Densospordes covens is Berry, forms with a that in the Middle Carboniferous of the massive cingulum, and species of the related Donetz Basin there is an almost complete genus Vallatisporites Hacquebard are repre• lack of spores with thickened fringes. Ish• sented. None of these species was common. chenko (1958) however records certain Spores very similar to Densospores regalis densospore species as characteristic spores have been. found in Visean coals from the at seven of the eight Namurian localities north of Engaland (Smith & Butterworth, examined from the Dnieper-Donet:.'1 Basin; in press) along with forms with a bizonate Hymenozonotriletes bialatus is the most re• cingulum referable to Cingulizonates bialatus current species, but H. eommutatus, Eury• (Waltz) Smith & Butterworth. Slightly zonotriletes erassipterus, H. intermedius higher in the sequence D. triangularis (Waltz) Ishchenko with verrucose ornament, Kosanke, with a massive cingulum, and and Trematozonotriletes variabilis are also Tholisporites scotieus Butterworth & Wil• mentioned. Only H. bialatus and H. eom• liams may be abundant; Cingulizonales d. mutatus are recorded from the Bashkirian. capistratus (Hoffmeister, Staplin & Malloy) Densosporites formosus Artiiz, with a Staplin & Jansonius, with a coarsely massive cingulum, similar to D. triangularis alveolate cingulum, appears in the upper• Kosanke, is stated by Artiiz (1957, p. 259) most Visean. to be the only densospores species charac• Hacqnebard's (1957) and Playforcl's teristic of the Namurian Alimolla Seam of (1963b) descriptions of spores from the the Zonguldak area of Turkey. Agrali Horton Group of Jova Scotia contain few (1964) records the occurrence of densospores references to spores of the densospore having massive, cristate and bizonate cinguli group; Vallatisporites, not dissimilar to throughout the Namurian of the Amasra Radiizonales, however is a related form Basin; they attain their greatest. frequency morphologically and is abundant in four of in the middle of the Namurian where they Playford's samples (l.e., TABLE 1, p. 38) constitute from five to ten per cent of the and Cristatisporites is present but rarely assemblagcs of the two lower seams exa• common. Staplin (1960, p. 3, FIG. 2a) mined, and from 25 to 50 per cent of the obtained almost 20 per cent of densospores assemblages of the highest seam (l.e., FIG. 1). from the underclay of a coal in the Golata The dominant. species present is Denso• Formation of Alberta (Visean); these were sporites marginatus Artiiz (d. Cingulizonales mainly spores with a massive cingulum but bialatus) . included a markedly bizonate species, Cin• Horst (1955) records very high numbers gulizonates landesii (Staplin) Staplin & of an indeterminate densospore (? Denso• Jansonius, and Densosporites spimfer Hoff• sporites intermedius Butterworth & Wil• meister, Staplin & Malloy, with apiculate liams) in the upper part of the Namurian A ornament of the cingulum. A Visean coal of Western Upper Silesia, especially in from the South Nahanni River area of the Andreas Seam (l.e., p. 185), and also Canada (HACQUEBARD & BARss, 1957) in the Sattelfl6z Group (Namurian B) of the contained 23 per cent of Densosp01'ites, most Mahrisch-Ostrau region, which contains a 20

single thick coal scam. Dyboya & Jacho• tratus (Hoffmeister, Staplin & :\lalJoy) wicz (1957) give detailed tables of spore Staplin & Jansonius are abundant and frequencies in Upper Silesia \\'hich include Del1sosporites intermedius Butterv,'orth & data for the genera Anulatisp01'ites (inter• Williams, D. pseudoal1nulatus Butterworth pretated by these authors as spores with & Williams and D. triangularis (with which an alveolate or pitted cingulum), Densos• D. spongeosus Butterworth & Williams is porites, including Cristatisporites, and synonomous) are common. At slightly Cing2tlizonatcs, including Radiizonates. Den• higher horizons in the ]\'amurian of the sosporites, mainly D. granulatus Dybova South Pennines :t\eves (1961) found Den• & J acho\\'icz, comparable to D. trial1gu• sosporites spinosus Dybova & J achowicz latus Kosanke, and D. ,'errueoslls Dybova (approaching Cristatisj>orites in form) to be & J achowicz, approaching the genus common in some coals and marine shales. Cristatisporites in its density of omament, Hacquebard, Barss & Donaldson (1960) reach peaks of a little less than 30 per cent record Densosporites from the Canso Group in the Namurian A and of more than 70 per (?Namnrian A) of Nova Scotia, but give no cent in the Namurian BjC. Anulatisporites, frequencies. mainly Densosporites (Anu1atisJ>orites) The genus Densosporites ,vas first des• anulatus (Loose) Schopf, Wilson & Bentall cribed by Berry (1937) from the Pennington (1944), A. baeeatus Dubova & Jachowicz Coal of Tennessee, of Mississippian age; and A. coronatus Dybova & J achowicz, the assemblage contained several spores both alveolate, reach peaks of 60 per cent with a massive cingulum, including the type in the lower part of the Namurian A and at species of the genus - D. covens is Berry. the junction of the Namurian A with the Hoffmeister, Staplin & Malloy (1956b, P. ]\'amurian BjC. Moderate numbers of 378) state that Densosporites is a charac• Cing1flizol1ates [C. tuberos'lls Dybova & teristic genus of Upper Mississippian and J achowicz and C. radiatus Dybova & J acho• Lo\\'er Pennsylvanian rocks generally. In wicz, comparable to C. bialatus and Radii• the Hardinsburg FOllnation of Kentucky zonates striatu.s (Knox) Staplin & J ansonius and Illinois (Lo\\'er Namurian or Upper respectively] occur in the Namurian A and Visean in age, containing the genera Rotas• are more common (about 15 per cen t) in the pora and Tripartes) they record from one to T amurian BjC where they occur along \\,ith sixteen per cent of Del1sosporites at all C. asteroides Dybova & Jachowicz and C. horizons examined (I.e., p. 377, TABLE 1). karezewskii Dybova & J acho\\'icz, analogous Densosporites inter111edi1tS, with \\'hich D. to Radiizonates aligerens (Knox) Staplin temu's HoffmeistE.r, Staplin & ~Ialloy is & J ansonius and R. rotatus (Kosanke) synonomous, is the ouly abundant species Staplin & J anson ius respectively. In the noted. Schemel (1950) recorded 92 per Bug Basin Densosporites and C1'ngu1izonates cent of densospores from a coal of similar both reach maximum percentages in the age from Daggett County, Utah; they higher part of the Namurian (J ACHOWICZ, were referred to Densosporites dominatoris 1964, PL. 2, and p. 1203) and Radiizonates Schemel and are not unlike D. intermedi2ts. (Cingulizonates) asteroides Dybova & J acho• wicz first appears at these horizons. 4. Westphalian Neves (1964) records abundant Denso• sporites anulatus, D. spinos1~s Dybova & Ishchenko (1958) lists no densospores J achowicz, D. triangularis and Radiizonates among the characteristic species present in striatus from lower Namurian coals in Nor• Moscovian coals of the Dnieper-Donetz thern Spain. Higher in the sequence these Basin but includes Hvmenozonotriletes species occur along \\·ith Densosporites bialatus and H. eommu,tatus in the lists for erassigramfer Artiiz, D. 111 ieroal1atolieus the two Bashkirian sequences examined. Ac• Artiiz (forms with ornament intermediate cording to his frequency table (I.e., TABLE between those of CristatisplJrites a.ncl Ci71/{U• 3) the~e species do not persist above the lizonates) and D. sphaerotriangularis Kosanke. Bashkirian and are the only hra densospores British -amuriall A coals with assem• to survive the Xamurian A. blages containing the genera Rotaspora and Artiiz (1957) records a varied suite of Tripartites have been describecl by Butter• densospores from the Westphalian A Sulu worth &. Williams (1958) from Scotland. and Biiyiik Seam of the Zongulclak area of In these coals Cingulizol1ates d. eapis- Turkey; this includes Densosporites lIIiero- BUTTERWORTH - THE DISTRIBUTION OF DENSOSPORES 21

silvanus Art iiz, a granulate form with a Cristatisporites-like D. verrucosus Dybova massive cingulum, D. adornatus Artiiz and & jachowicz and D. spinosus Dybova & D. marginatus Artiiz, forms with a bizonate Jachowicz in the Westphalian A, and hy D. cingulum referablE. to Cingulizonates, Den• decorus Dybova & Jachowicz [equated by sospordes jlal1us Artiiz, and the rather these authors, p. 163, with Cristatisporites unusual D. microponticus Ariiiz and D. indignabunj.,us (Loose) Potonie & Kremp] microanatolicus Artiiz, crist ate forms which at highr·r horizons. A nulatisporites .I=ersists also exhibit an inner thickening of the throughout at lower levels of frequency cingulum. D. microanatolicus and an un• but may reach 20 or 30 per cent in the lower named species cf Densosporites wtre also part of the Westphalian B. Ct'ngulizonates abundant (10 to 30 per cent) in the West• reaches a peak of 30 per cent in the middle phalian C Kalin and Ara Seams of the part of the Westphalian A and is not recor• Amasra-Tarlaagzi Basins (AInuz, 1963). ded from above the Westphalian B. The Agrali (1964) records extremely varied and main species in the Westphalian A is C. abundar. t densospore assemblages from the tttberosus Dybova & j achowicz, analogous to Westphalian of the Amasra Basin. These C. bialatus, and the Radiizonates-like species spores are present in all of the seams ex• C. asteroides Dybova & J achowicz and C. amined, constituting over 50 per cent of the lwrczewskii Dybova & J achowicz also occur; assemblages of several seams in the West• these latter pelsist into the Westphalian B phalian A and B and the lower part of as important species. the Westphalian C, and ranging from five In the Bug Basin of Poland (JACHOWICZ, to 25 per cent in the upper part of the 1964. PL. 2) Densosporites is common Westphalian D (l.c., FIG. 1). The ranges throughout the Westphalian, decreasing given for the 22 species considered are long slightly towards the top of the sequence, and very much at variance with their ranges and Cinguhzonates is common at the base elsewhere; no photographs or descriptions of the Westphalian A, but thereafter are given to support the identifications becomeo; Itss frequent and disappears in made. Forms with a massive cingulum the lower part of the Westphalian C. and cristate and bizonate forms range from Cristatisporites (J ACHOWICZ, in Discussion the Westphalian A to the Westphalian D; of BUTTERWORTHet al., 1964a, p. 1055) is Densosporites lobatus Kosanke, with a mas• confined to the Westphalian. sive cingulum, is one of the most abundant Grebe (1962) has listed the frequencies species throughout the Westphalian Band of Densosporites (including Cristatisporites) C. Radiizonate forms extend from the and Anulatisporites in the Westphalian B middle of the Westphalian A to the top of and C coals of the Ruhr. She shows (I.e., the Westphalian D and Radiizonates (Den• TABLE 1) that Anttlatisporites, mainly sisporites) jaunus (Ibrahim) Butterworth Densosporites (Anulatisporites) anu!atus, is & Smith is one of the dominant species of most prevalent in the Westphalian Band the Westphalian C. only occasionally reaches frequencies greater Neves (1964) records Densosporites micro• than 20 per cent. Densosporites seldom al1atolicus from the Westphalian A of Nor• exceeds a frequency of 50 per cen t but thern Spain, where it occurs in association may be greater than 60 per cent in the with Densosporites crassigranijer Artiiz, a lower part of the Westphalian C where it bizonate species with radially arranged reaches a maximum. D. sphaerotriangularis verrucae, Densosporites anulatus, D. sphaero• Kosanke may be prominent in the West• triangt,laris and Radiizonates (Densospo• phalian B but. the most common species, rites) striatus. particularly in the Westphalian C, is Radii• Dybova & Jachowicz (1957) record zonates (Densosporites) jatmus (Ibrahim) copious densospores from the \,yestphalian Smith & Butten,·orth. Other species, of Upper Silesia. As a genus Densosporites including those which would be assigned to (I.e., TABLE 168) reaches peaks of almost Cingulizonates, are rare. Cristatisporites 30 per cent in the Westphalian A and B indl;gnabunchts (Loose) Potonie & Kremp and peaks of more than 70 per cent in the and C. connexus Potonie & Kremp, spincse Westphalian C. In the Westphalian D it and verruccse forms respectively, seldom tends to decline. The most prominent exceed 10 per cen t. species throughout is D. granulattts Dybova These results compare with thoo;e of & J achowicz; this is accompanied by the Kremp (in BHARADWA] & KREMP, 1955, 22 THE 1>ALAEOBOTANIST

TABLE 3, p. 57) in which the presence is Turning to the limnic coal basins of also noted of Densosporites sphaerotriangu• Europe, Bharadwaj (1955, 1957a) has de• laris in the Westphalian A coals of the Ruhr. scribed a suite of densospores from the up• Bharadwaj & Kremp (I.e., TABLE 5, & per part of the Westphalian C of the Saar; BHARADWA], 1957b) found no densospores this includes D. sphaerotriangularis, D. lori in the Velener Beds which lie_above the Bharadwaj, a bizonate species, Cristatispo• Dorstener Beds, the highest horizons ex• rites elegans Bharaclwaj and C. saarensis amined by Grebe; the Velener Beds are said Bharadwaj, which are notable for their to lie at the base of the Westphalian D. small size - all, excepting the first, are less Pierart (1962) records abundant Denso• than 50 microns in diameter. sporites (A nulatisporites) awulatus from the The distribution of Westphalian denso• Westphalian B of the Mons area of Belgium. spores in the French coal basin of Lorraine Other species of Densosporites, including is summarized by Alpern (l963b, p. 2) who those which "vould be assigned to the genus divided the group into Cingulizonates and Cingulizonates, are not common and Crista• Cristatisporites, forms with a massive cingu• tisporites is recorded from onlv two horizons lum being either not present or not con• (I.e., TABLE 2). Densosporites is also some• sidered. The specimens photographed are times abundant in the Westphalian A and not so small as those described hy Bharad• B of the Belgian Campine (NOEL, in BUTTER• vvaj from the Westphalian C of the Saar. WORTHet al., 1964b); in the upper Westpha• Critatis/Jorites is fairlv common in the West• lian C Pierart (1958) records Radiizonates phalian B, reaches a maximum of 65 per (Densosporites) faun us and Densosporites cent in the Westphalian C, ranges from 8 to sphaerotriagnularis throughout, and a species 30 per cent in the lower part of the West• of A nulatisporites from several horizons. phalian D, and then disappears. Cinguli• Alpern (1959, p. III of complement) zonates is confined to the Westphalian B records about 5 per cent of Densosporites and C where it maintains a frequency of from the Westphalian B of the Pas de Calais about 25 per cent. Venkatachala & Coalfield. Bharaclwaj (1962, p. 195) record less than In Britain densospores have been found one per cent of Cristatisporites in one of the at all Westphalian horizons with the excep• 13 coals examined by them from the West• tion of the higher part of the W es tphalian phalian D of Faulquemont Colliery, Lorraine. C where there is a notable hiatus (Smith In Spain Wagner (in Discussion of & Butterworth, in press). Lower West• WAGNER, 1962, p. 762) has indicated that phalian A horizons are characterized by Densosporites occurred in a sample examined Densosporites anulatus and Radiizonates from the Westphalian C of Lieres (Asturias) ; striatus. Densosporites sphaerotriangularis examination of vVagner's material and and species of Cristatisporites appear at unpuhlished photographs has indicated that about the middle of the Westphalian A these are forms with a massive cingulum, and remain abundant almost to the top of or radiizonate forms not unlike R.Jaunus. the Westphalian B vvhere they tend to be In the Maritime Provinces of Canada, replaced by Cingulizonates loricatus (Loose) Hacqnebard, Barss & Donaldson (1960, Butterworth & Smith and Cristatisporites FIG. 2) record Densosporites and Cristati• solaris (Balme) Butterworth & Smith in the sporites in the lower part of the Westphalian lower part of the Westphalian C. Radii• A (Howley Beds of Newfoundland), the zonates aligerens (Knox) Staplin & ]ansonius latter genus only in the upper part of the and R. striatus characterize the higher part Westphalian A (Riversdale Group), Crista• of the Westphalian A, Radiizonates tenuis tisporites and rare Densosporites in the (Loose) Butterworth & Smith the West• Westphalian B (Cumberland Group) and phalian B, and R. faunus the lower part of Critatisporites in the Lonchopteris Zone of the Westphalian C. Higher in the West• the Westphalian C. Densosporites is record• phalian C omaller species of Cristatisporites ed from one seam only in the lower part such as C. saarensis Bharadwaj may of the Westphalian D. occur. In the southern part of the country The most comprehensive description of spores indistingui,hable from Densosporites Westphalian c1ensospores in North America sphaerotriangularis, except for their smaller is that given by Kosanke (1950) for the size, have been found in Westphalian D Pennsylvanian of Illinois. He found coals. Densosporites (I.e., PL. 17) to be restricted BUTTER\VORl'H - THE DISTR IBUnOi' Or. DE~SOSPORES 23 entirely to the Tradewater and Caseyville Pennsylvanian of Indiana. He ascribed Groups. This range corn.sponds to the the spores to two species only - Dcnsospo• Westphalian A-C (Kosanke, in Butterworth rites reynoldsbttrgensis (equals D. anulatus) et al., 1964b, TABLE 1). Densospores are and D. lo!Jatus Kosanke which includes abundant only in thc Reynoldsburg Coal forms with a massive or slightly differen• towards the base of the sequence in which tiated cingulum. Peaks of abundance are D. reynoldsbu.rgensis Kosanke (D. anulatus) shown (l.c., FIG. 7) at a low horizon in the is the chief species present (KOSANKE, 1950, Mclllsfield Formation and at an horizon in p. 31). Elsewhere in the sequence Kosanke the 10\\ er part of the Brazil Formation (personal communication) has indicated that higher in the sequence. Densosporites lobatus Kosanke is the most Cropp (1960) found Densosporites to be representative speciEs and that forms attri• continuously present throughout coals of butable to the genera Crista#sporites and Pottsville age (Westphalian A to C approxi• Cingulizonates are much less prominent mately) in the Warrior Basin of Missis• than at equivalent horizons in Europe. sippi and Alabama; they Wfre abundant in Radiizonates difforlllis (Kosanke) Staplin three coals towards the middle of the & Jansonius and R. rotatus (Kosanke) sequence (l.c., TEXT-FIG. 4). The same author Staplin & J an~onius are restricted to a (CROPP, 1963) described, at generic level, few coals towards the base of the Trade• the spore contents of 15 coals from the water Group. Pennsylvanian of Tennessee and found Cross (1947) in a preliminary study of Densosporites to be common in most of them miospore distribution in the lowcr part of ann abundant ill a few. By analogy with the Pennsylvanian in the Appaketian the word of Kosanke (1950) he concluden region, noted the presence of Denso• that the strata concined roughly with the sporites, particularly in the Alma Seam Caseyville, Abbott and Spoon Formations where it is the dominant spore (l.c., p. (Westphalian A to C; Caseyville and Trade• 305). This work was expanded by Cross water Groups of Kosanke, 1950). & Schemel (1952) who compared the ranges of the genus Densosporites in the 5. Stephanian and Permian Western Interior Basin (Schemel's work). the Easter Interior Basin (Kosankc's work) Pierart (1956, PL. 5, FIG. 7) figures den• and the Appalachian region (CROSS& SCHE• sospores with spinose ornament from the MEL, 1952, FIG. 4). They found that the French limnic basins of Blan£v and Decaze• upper limit of the genus occurred at almost ville (Middle, and Middle and Upper Stepha• equivalent horizons in all three regions, viz. nian respectively). and Doubinger (1958) near to the base of the Carbondale Formation. rccords high numbers of densospores with Hoffmtister, Staplin & Malloy (1955a) a massive cingulum, sometimes slightly compared the known ranges of all miospore ornamented, from the Decazcville Basin, genera in Iorth America with their ranges but found them to be less common at Saint• elsewhere in the world. They state that Perdoux (IDEM, 1951). the genus Densosporites reaches its maxi• Alpern (1959, p. III of complement; mum frequencies in the uppEr part of the 1960, PL. 19) has indicated that clensospores Mississippian and the lower part of the .disappear in the Westphalian D of France Pennsylvanian; they quote the range given .and reappear in the Lower and Middle above and also note the occurrence of den• Stephanian; they diminish again and are sospores in the uppermost Pennsylvanian extremely rare in the Upper Stephanian of West Texas. and Permian. Further details of the Wilson & Hoffmeister (1956) described Stephanian roals of Lons in the Jura Cirratriradites intermedius from the West• (ALPERN, 1959, pp. 231, 232) indicate that phalian D Croweburg Coal in Oklahoma. the densospores present are very similar to This spore (I. C., PL. 2, FIG. 9) has the ap• some of the Westphalian B species - Den• pearance of a densospore with a relatively sosporites lobatus Kosanke, D. sphaerotrian• narrow, massive cingulum. In the Crowe• gularis Kosanke, D duriti Potonie & Kremp burg Coal samples 'its greatest frequency {a slightly more ornate form of D. sphaero• was 5·5 per cent, average 1·3 per cent. tY1'angularis), Crisiat£s!,orites indignabundus Guennel (1958) recorded abundant den• (Loose) Potonie & Kremp and C. solan's sospores at certain horizons in the lower (Balme) Butterworth & Smith. On the 24 THE P.\L\EOBOT.\NIST

whole however they tend to be larger• described by Imgrund (1960) from the Densosporites major Alpern, whlCh is restrict• Kaiping Basin of China. ed to the Stephanian, has a diameter of In North America Hoffmeister, Staplin from 100 to 160 microns. Alpern (1959, & :\'la11oy (J 955a) note the occurrence of pp. 232, 246) has demonstrated thal in the ? Densosporites and Cristatisporites in the LOllS area the densospores have a cyclic Upper Cisco (Pennsylvanian) or Lower dif.i.ribution which is of use in the correlation Wolfcamp (Permian) of North Texas (l.c., of the coals. Densosporites is rare in the p. 13). Peppers (1964) has recorded about Decize Basin (ALPERN, 1959. p. 284) and one per cent of Densosporites from clastic less than one per cent of Cristatisporites sediments at several horizons in the Mc• are recorded by Alpern (1963a, p. 2) from Leansboro Group at the top of the Pennsyl• the coals in the upper part of the Stephanian vanian; he attributes these occnrrences and the base of the Autunian of St. Etienne. either to the reworking of older sediments On the other hand no' densospores were or to the continued growth of the parent recorded by Alpern (1959) in the Stephanian plants in areas outside those of coal forma• coals of Lorraine (lVIORSBACH,l. C., p. 266), tion (l.c., p. 60). the Loire Basin (TRIOLLIERE, l. C., p. 275) or from the Permian coals of the Aumance SUMMARY OF OCCURRENCES Basin (l.c., p. 296). Bharadwaj & Venkatachala (1957, p. 9, Densospores are first recorded from the TABLE 4) record less than 5 per cent of a Devonian of Russia, Scotland, France and species of Densosporites from an upper North Africa, and, in very low numbers, Stephanian C coal in the pfalz Basin, and from the Canadian Arctic. unassigned densospores are recorded by The earliest densospores with a more Kalibova (1962, PL. 4, FIG. 1) from the Carboniferous aspect, that is with a smaller Stephanian Kounov Seam of the Kladno• size and without the grapnel-like ornament Rakovnik Basin, and by the same author characteristic of Devonian spores in gen~ral, (1964) from a Lower Stephanian coal of the are described fcom the Lower Carboniferous Plzen Basin; further details of each of these of northern latitudes, with the greatest latter occurrences are to be published later. diversity occurring in Spitsbergen. Bharadwaj (1955, 1957a) (loes not record By Namurian times the plants producing any densospores from t.he Stephanian coals densospores had passed their peak in Euro• of the Saar. pean Russia bu t ft.ourished in Canada, Britain, In the limnic basins of Spain Wagner (in Silesia and, further south, in the United Discussion of WAGNER, 1962, p. 762) has States, Northern Spain and Turkey. The indicated that Densosporites occurs in three greatest diversity in the assemblages OCC'Jr• samples investigated from the Stephanian red at the European localities. B/C of Puertollanc (Cuidad Real) and that The group declined in the upper part of in two of these they were particularly abun• the Namurian in European Russia and in dant; one of the seams was No. 3 Coal of t.he middle of the Westphalian in orth Santa lVIaria Colliery and all were samples America. The most varied Westphalian from which Dijkstra (1955) has publishfd A assemblages occur where the underlying descriptions of megaspores. Examination Namurian assemblages are also varied but of Wagner's material and unpublisheq in the Westphalian Band C the centres of photographs has indicated that the spores diversity moved to the coalfields of northern are highly ornamented, approaching Cris• Europe, and densospores occurred for the tatisporites in form. first time in the European limnic fields. Zonate densospores with a crenulate There was a general decline in densospore• flange and prominent laesurae extending producing plants in the Westphalian D but to the equator have been isolated from sandy they persisted, patchily, in the Stephanian shales, of probable Permian age, from the and Permian of the linmic basins. Eastern Desert of Egypt (SCHURMA~', No densospores have been recorded from BURGER & DrJKsTRA, 1963, PL. 1, FIG. 2). the Tunguska area (Angara) of Asiat.ic Densospores were not found in the Upper Russia or from the Kaiping Basin of China. Carboniferous coals of the Donftz Basin Comparisons among the frequencies of described by Luber & Waltz (J 941) or in the various genera present at different the Stephanian and Permian assemblages localities must be treated with caution since BUTTERWORTH - THE DISTRIBUTIOX OF DEXSOSPORES 25

llot all of the assemblages have heen de• the lype to yield dcnsosporcs; in Britain scribed in the same detail. The forms de• the red beds, represen ting ariel, uplifted scribed from I orth America are restricted areas, form the whole of the upper part of in variety, having either a massive cingulum the Wes tphalian in the northern part of the or one which is weakly bizonate or cristate; country; further south, in the English Mid• forms with a bizonate cingulum appear to lands, the red beds of the Westphalian C, dominate in European Russia. Bizonate the Etruria Marl, are succeeded by more and radiizonate forms are not generally coal-beal ing rocks but in these the coals, found above the vVestphalian C although which arc generally thin and impersistent, thev are recorded from the Westphalian D do not contain den ospores. Tt is only in of turkey and a related form occurs in the the coal fields of the extreme south of the Permian of Egypt. country that conditions in the Westphalian D were suitahle for the growth in any num• DISCUSSION bers of the densospore-bearing plants. In Europe there are fe,,' Carboniferous The foregoing data are fragmentary and coal . equences in \"hich densospores do future investigations will doubtle,:s disclose not occur, and these sequences are not the presence of further densospore-rich coal extensive. In Russia and North America horizons. There' i.3 sufficient evidence on the other hand there are long sections however to demonstrate that. the den so• of coal-bearing strata from which densospores spores, which have been used by various have not been recorded. A particularly workers, including the present author, as detailed account of one such section is time indices, have widely difff:'rent strati• available for the mionis Basin (KOSAC\TKE, graphical ranges in different parts of the SIMON, WAC\TLESS& WILL"r.-\~, 1960) from northern hemisphere. Although they are which Kosanke (1950) has described the frequently present in Carboniferous coal miospore assemblages. The Pennsylvanian seams there are extensive sequences of cOJ.ls of Illinois is divided into three groups: the in which they do not occur. vVhen present, McCormick Group at the base consists of their numbers and variety show considerable the Caseyville and Abbott Formations and variation between localities. In general is characterized by thick sandstones, thin the diversity of densospores is greatest in discontinuous coals and rare limestones; the Spitsbergen and other northern areas in the succeeding Kewanee Group, including the Lower Carboniferous, and in European Spoon and Carbondale Formations, has more localities in the Upper Carboniferous. widespread coal development, fewer sand• The longf'st ranges of densospores are stones and "'idespread limestones of uniform found, as might be expected, in the paralic thickness; and the McLeasnboro Group at basins of the continental shelf areas (Britain, the top of the sequence has thick, abundant Poland and Upper Silesia) and other areas limestones and thin coal seams. The den• such as the Turkish Amasra Basin where sospores recorded by Kosanke (1950) are because of the relative stability the forma• rest ricted to the coals of the McCormick tion of coal itself waS most prolongefl. Group and to the Spoon Formation of ,the Elsewhere, in the areas of the foredeeps, Kewanee Group. They are prominent at various parts of the sequence are represented only 1\"0 horizons in this sequence and show by marine beds and coal fcrmation was relatively little variation in form. The thus delayed or brought prematurely to an Carbondale Formation contains coal seams end. Even in the shelf area, in Britain for from two to seven and occasionally fifteen instance. coal formation was possible in feet thick; the al;scnce of densospores from Visean and Namurian times only in the such an apparently congenial environment, northern part of the country; further south and at horizons equivalent to those at which the Coal ~'Ieasures-type rocks are replaced they were presen t else"'here in the northern by limestone sequences. Coal formation hemisphere, suggests that the prohibiting generally, and the presence of the plants factor may have been climatic, most likely producing densospores in particular, were a decrease in humidity (see SMITH, 1964). also impeded by the effects of earth move• It is conceivable that the climatic changes ments. The coal swamps which became which led to the disappearance of denso• established after the various movements spores in the upper part of the Westphalian had died down were only occasionally of C in parts of Europe were also responsible 26 THE P,\LAEOBOTA~IST

for the decline of the densospores in Illinois; presence may be further controlled by in Europe the climatic changes were closely considerations of climate. followed by uplift of the land areas which It is concluded that densospores can be precluded the formation of coal, whereas used as stratigraphic indices only when in Illinois coal formation continued but their ranges within a particular area are without the development of the type of known. 5wamps in which the plants producing densospores thrived. ACKNOWLEDGEMENTS The work described was carried out III CONCLUSIONS the Department of Geology, University of Sheffield while the author was in receipt of Densospores cccur m coals deposited a grant from the National Coal Board, which between the Middle Devonian and the is gratefully acknowledged. The author Autunian in the Euranevican Province of wishes to thank her colleagues in the C.I.M. P. the northern hemisphere. They first appear Working Groups NO.2 ---.:.Densosporites and in the more northern latitudes and are dis• No. 13C - Namurian and Westphalian placed gradually southwards. The youngest stratigraphy, for their generous help in the densospores occur in the European limnic compilation of some of the dala on which basins. this paper is bhsed. Thanks are also due Densospores are most varied and abun• to Dr. A. H. V. Smith and R. H. Wagner dant in Western Europe, especially in regions for their helpful criticisms of the manuscript, of slow subsidence such as continental shelf and to the latter for his kindness in allowing areas where they tend also to have the the author access to his unpublishecl longest stratigraphical ranges, but their matc.ria1.

REFERENCES

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V Congr. illi. 81ml. Ceol. Carb., Paris 3: 1049• HORST, U. (1955). Die Sporae dispcrsae des Namurs 1057 (B .. \lpern, M. S. Barss, H. Grebe, R. M. von Westoberschlesien und J\Iahrisch-Ostrau. Kosanke, W. J\1. Muller, R. Noel, P. Pierart, Palaeontographica, 98B: 137-236. A. H. V. Smith & H. J. Sullivan) HUGHES, N. F., DETTMANN,M. E. & PLAYFORD,G. Idem (1964b). Miospore distribution in the Namu• (1962). Sections of some Carboniferous dis• rian and \Vestphalian. Report of C.1.M.P. persed spores. Palaeontology, 5: 247-252. working group no. 13C, Ibid, 3: 1115-1118. IMGRUND, R. (1960). Sporae dispersae des Kai• CHALONER,\V. G. (1958). A Carboniferous Sela• pingbeckens. Geol. Jb., 77: 143-204. ginelliles with Densosporiles microspores. Pa• ISHCHENKO, A. l\L (1956). Spores and pollen of laeonlology, 1: 245-253. the Lower Carboniferous deposits of the western Idem (1962). A Sporangioslrobus with Densos• extension of the Donetz Basin and their strati• poriles microspores. Ibid. 5: 73-85. graphical importance. Akad. Nauk Ukrrtinian CROPP, F. W. (1960). Pennsylvanian spore floras S.S.R .. 11: 1-185. (In Russian) from the Warrior Basin, Mississippi and Ala• Idem (1958). Sporo-pollen analysis of the Lower bama. J. Paleont., 34: 359-367. Carboniferous sediments of the Dnieper-Donetz Idem (1963). Pennsylvanian spore succession in Basin. Ibid, 17: 1-188. (In Russian) Tennessee. Ibid. 37: 900-916. J ACHOWICZ,A. (1964). ~euere Forschungen uber CROSS, AUREAL T. (1947). Spore floras of the die Mikroflora des polnischen Karbon. C.R. V. Pennsylvanian of \Vest Virginia and Kentucky. Congr. inl. Siral. Carbo Glol., Paris. 3: 1201• J. Geol., 55: 285-308. 1214. CROSS, AUREALT. & SCHEMEL,M. P. (1952). R• KALIBOVA, 1\1. (1962). Sporenerforschung im presentative microfossil floras of some Appa• Kounov-Floz des Schachts Framtisek in Lhota lachian coals. C.R. III. Congr. into Sirat. Carb., pod Dzbanem im Klando-Rakovnik-Becken. Heerlen, 1: 123-130. Sbornik U.U.G., palaeont. 27: 81-100. DIJKSTRA, S. J. (1955). Megaspora carboniferas Idem (1964). Palynological investigation of the espanolas y su emplo en la correlacion estrati• Lower Nevren Seam (Lower Stephanian) in grafica. Esludios Geologicos, C.S.I.C. Inslituto the northern part of the Plzen Carboniferous " Lucas Mallada ", Madrid, 11: 277-354. Coal-basin. Sbornik Ceologickych ved, Palaeont. DOUBINGER, J. (1951). Sur quelques microspores 4: 1-128. du bassin du Saint-Perdoux (Lot). Congres KOSANKE, R. 1\1. (1950). Pennsylvanian spores de I'A.F.A.S., Perigneux, 1957. of Illinois and their use in correlation. Bull. Idem (1958). Les microspores du bassin de Ill. geol. Survey, 74: 1-128. Decazeville (Aveyron). Revue Industr. min., KOSANKE, R. M., SIMON, J. A., WANLESS, H. R. speciale no., 15 (vii) 58: 12-15. & WILLMAN, H. B. (1960). Classification of DYBOVA,S. & J ACHOWICZ,A. (1957). :Microspores the Pennsylvanian strata of Illinois. Ill. geol. of the Upper Silesian Coal Measures. Insl. SU1'V. Report of Investigations, 214: 1-84. Geol. Prac. Warsaw, 23: 1-328. (In Polish and LUBER, A. A. (1935). Les types petrographiq ues Czech.) de charbons fossils Spitsbergen, Chimic Com• GREBE, H. (1962). Zur Verbreitung der Sporen bustible Solide. 6: 186-195. (In Russian) im oberen \Vestfal B und dem \Vestfal C des LUBER, A. A. & WALTZ, 1. E. (1941). Atlas of Ruhrkarbons. Forlschr. Geol. Rheinld. u. Weslj. microspores and pollen grains of the Palaeozoic 3: 773-786. of the U.S.S.R. Tr. All-Union Ceol. Sci. Res. GUENNEL, G. K. (1958). Miospore analysis of the Inst. (V.S.E.C.E.I.) 139: 1-107. (Geological Pottsville coals of Indiana. Bull. Ind. geol. Survey of Canada transla-tion, circulated by Survey No. 13: 1-101. Humble Oil and Refining Company, from ori• HACQUEBARD,P. A. (1957). Plant spores in coal ginal Russian.) from the Horton Group (Mississippian) of Nova MCGREGOR, D. C. (1960). Devonian spores from Scotia. jl£icropaleolltology, 3: 301-324. J\IelvilIe Island, Canadian Arctic Archipelago. HACQUEBARD,P. A. & BARss, M. S. (1957). A Palaeontology. 3: 26-44. Carboniferous spore assemblage in coal from NAUMOVA, S. N. (1953). Sporo-pollen complexes the South Nahanni River area, Northwest of the Upper Devonian of the Russian Platform Territories. Bull. geol. S~trv. Can. ~O. 40: 1-63. and their stratigraphical value. Tr. Inst. HACQUEBARD,P. A., BARSS, 1\1. S. & DONALDSON, Ceol. Nauk A/lad. Nauh S.S.S.R. 143: 1-204. J. R. (1960). Distribution and stratigraphic NEVES. R. (1961). Namurian plant spores from significance of small spore genera in the Upper the Southern Pennines, England. Palaeonto• Carboniferous of the Maritime Provinces of logy. 4: 247-279. of Canada. C.R. IV. Congr. into Strat. Carb., Idem (1964). The stratigraphical significance of Heerlen, 1: 237-245. the small spore assemblages of the La Camocha HACQUEBARD,P. A. & DONALSDON,J. R. (1964). Mine, Gijon, N. Spain. C.R. V. 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Idem (1962). Observations sur la palynologie du of crassidurite in coal seams in Yorkshire. \Vestphalien B et C de la partie occidentale du Geol. Nlag., 94: 345-363. Massif du Borinage. Cimtre National de Geo• Idem (1960). Structure of the spore wall in certain logie Houittere, Xo. 5: 103-110. miospores belonging to the Series Cingulati Pot. PLAYFORD,G. (1962). Lower Carboniferous micro• and Klaus. Palaeontology, 3: 82-85. floras of Spitsbergen. Palaeontology, 5: 550• Idem (1962). The palaeoecology of Carboniferous 618. peats based on the miospores and petrography Idem (1963a). Lower Carboniferous microfloras of bituminous coals. Proc. Yorks. geol. (polyt) of Spitsbergen - Part 2. Ibid. 5: 619-678. Soc., 33: 423-474. Idem (1963b). Miospores from the Mississippian Idem (1964). Zur Petrographie und Palynologie Horton Group, Eastern Canada. Bull. geol. der Kohlenfloze des Karbons und ihrer Beg• Surv. Can. 107: 1-47. leitsehichten. Fortschr. Geot. Rheinld. u. Westj., PLAYFORD, G. & BARSS, M. S. (1963). Upper 12. YIississippian micro flora from Axel Heiberg SMITH, A. H. V. & BUTTERWORTH,M. A. (in press) Island, District of Franklin. Pap. geol. Surv. Miospores of British Carbofliferous coal seams. Can. 62-36: 1-5. STAPLIN, F. L. (1960). Upper Mississippian plant POTONIE, R. & KRDfP, G. (1954). Die Gattungen spores from the Golata Formation, Alberta, der palaeozoischen Sporae dispersae und ihre Canada. Palaeontographica, 107B: 1-40. Stratigraphie. Geol. Jb., 69: 111-194. STAPLIN, F. L. & JAN JANSONIUS, (1964). Eluci• RICHARDSON,J. B. (1960). Spores from the Middle dation of some Paleozoic densospores. Palaeon• Old Red Sandstone of Cromarty, Scotland. tographica. 114B: 95-117. Palaeontology, 3: 45-63. SULLIVAN, H. J. (1964a). Miospores from the Idem (1964). Stratigraphical distribution of some Lower Limestone Shales (Tournaisian) of the Devonian and Lower Carboniferous spores. Forest of Dean Basin, Gloucestershire. C.R. V. Report of C.I.M.P. working 13B. C.R. V Congr. into Strat.Geol. Carb., Paris, 3: 1249-1259. Congr. into Strat. Geol. Carb., Paris, 3: 1111-1114. Idem (1964b). Miospores from the Drybrook Idem (1965). Middle Old Red Sandstone Spore Sandstone and associated measures in the Assemblages form the Orcadian Basin, Xorth• Forest of Dean Basin, Gloucestershire. Pa• east Scotland. Ibid. 7: 559-605. laeonlology, 7: 351-392. SCHEMEL, M. P. (1950). Carboniferous plant THIESSEN, R. (1930). Splint Coal. Am. Inst. spores from Daggett County, Utah. J. Paleont. Min. Met. Eng. Trans., 644-672. 24: 232-244. VENKATACHALA,B. S. & BHARADWA],D. C. (1962). SCHOPF, J. 1\1., \YILSOX, L. R. & BENTALL, R. Sporological studies of the coals from Falken• (1944). An annotated synopsis of Paleozoic berg (Faulquemont) Colliery (Lorraine) France. fossil spores and the definition of generic groups. Palaeobotanist, 11: 159-207. Report of Invesligations, Ill. geol. Surv. 91: 1-72. WAGNER, R. H. (1962). A brief review of the SCHUR~[ANN,H. 1\1. E., BURGER, D. & DI]KSTRA, stratigraphy and floral succession of the Carbo• S. J. (1963). Permian near Wadi Arabia, niferous in N. \Y. Spain. C.R. Congr. into Eastern Desert of Egypt. Geol. en Mijnb., Strat. Carb., Heerlen, 3: 753-762. 24e: 329-336. WILseN, L. R. & HOFFMEISTER, W. S. (1956). S~fITH, A. H. V. (1957). The sequence of micros• Plant microfossils of the Croweburg Coal. pore assemblages associated with the occurrence Okla. grol. Surv. Circ. 32: 1-57.