350 AMERICAN JOURNAL OF BOTANY [Vol. 44. HEIMBECK, LOUISE S. 1954. On the etiology of brown SUSSMAN, M. 1955. Developmental physiology of the roots. Yellowing and wilt due to "B type (Dienes) amoeboid slime molds. In Biochemistry and physi­ L. (Kleinberger) forms" of bacteria, with special ology of protozoa. Vol. II, 201-223. Academic reference to pea wilt. Oslo. Published by author. Press. New York. MCCLiNTOCK, BARBARA. 1939. The behaviour in successive ---. 1956. The biology of the cellular slime molds. nuclear divisions of a chromosome broken at meio­ Ann. Rev. Microbiol. 10: 21-50. sis. Proc. National Acad. Sci. (U.S.) 25: 405-416. WILSON, C. M. 1952a. Sexuality in the Acrasiales. Proe. RAPER, K. AND C. TROM. 1941. fnterspecific mixtures B., National Acad. Sci. (U.S.) 38: 659-662. in the Dictyosteliaceae. Amer. Jour. Bot. 28: 69-78. SKUPIENSKI, F. X. 1920. Reserches sur Ie cycle evolutif ---. 1952b. Meiosis in Allomyces. Bull. Torrey Bot. des certains myxomycetes. Paris. Published by Club 79: 139-160. author. ---. 1953. Cytological study of the life cycle of Die­ STRAUS, J. 1954. Maize endosperm tissue grown in vitro. tyostelium. Amer, Jour. Bot. 40: 714-718. II. Morphology and cytology. Amer. Jour. Bot. 41: ---, AND I. K. Ross. 1955. Meiosis in the myxomycetes. 833-839. Amer. Jour. Bot. 42: 743-749. TETRAXYLOPTERIS SCHMIDTII GEN. ET SP. NOV., A PROBABLE PTERIDOSPERM PRECURSOR FROM THE DEVONIAN OF NEW YORK' Charles B. Beck IN EASTERN New York, Devonian strata have stone and the friable nature of the plant'material yielded large, well-preserved plant compressions the finer axes are however rarely found intact or from which a relatively complete knowledge of well-preserved. The Hawk's Nest material was col­ the external form of the plants has been obtained. lected by Prof. H. P. Banks. This material of only Generally, nothing has been discovered about the well-preserved compressions has supplied valuable internal anatomy of these plants. A source of corroborative information about external mor­ valuable information which has been largely neg­ phology. lected is the pyrite petrifaction occurring occa­ According to Chadwick (1935) and Cooper et sionally in direct association with the compres­ al. (1942) the Oneonta formation is correlated sions. Many of the fossil specimens on which this with the Cashaqua and Middlesex shales of the study is based are compressions with segments of Cenessee Valley and the Ithaca formation of the some axes structurally preserved in pyrite. This Cayuga Lake Region. In southeastern New York paper describes an Upper Devonian plant from and northeastern Pennsylvania the Delaware River eastern New York giving details of both internal sandstone is the equivalent of at least the upper' and external structure. portion or possibly the entire Oneonta formation MATERIALS AND LOCALITIEs.-The material on according to Willard (1936, 1939). These forma­ which this work is based was collected from Upper tions comprise the lower part of the Naples Group Devonian strata at two localities in New York: of the Finger Lakes Stage. (1) the Oneonta formation in Davidson Quarry TECHNIQUES.-The greatest technical problem near Davenport Center, Delaware County, and encountered was that of preparing the small sec­ (2) the Delaware River sandstone exposed in a tions of pyritized axes for microscopic examina­ road cut at Hawk's Nest on New York State route tion. Since pyrite is opaque it must be examined 97 near Port Jervis, Sullivan County. The David­ with reflected light. Great difficulty is usually en­ son Quarry material, collected by Dr. Victor countered in obtaining polished surfaces of such Schmidt of Brockport State Teachers' College, con­ sections because of the tendency for cut surfaces tains both compressions and associated pyrite petri­ to crumble during grinding and polishing. This factions. For this reason it is the more valuable tendency is intensified if a large amount of carbo­ material. Because of the coarseness of the sand- naceous wall material is present. Pyrite oxidizes rapidly when exposed to the atmosphere which 1 This paper is taken from a thesis presented to the Graduate School of Cornell University in partial fulfillment also causes crumbling. These difficulties were over­ of the requirements for the Ph.D. degree. The writer ex­ come by the use of an embedding technique de­ presses appreciation to Professor H. P. Banks of the De­ scribed in detail in a previous paper (Beck, 1955). partment of Botany for his genuine interest and able guid­ ance during the course of this work and for suggestions re­ More than 200 sections of the pyritized axes were garding the preparation of the manuscript. successfully prepared. The writer also acknowledges with appreciation the sug­ In attempts to isolate spores and cuticular re­ gestions made by Professor John Walton of the University, mains several maceration techniques were used Glasgow in whose department the manscript was prepared; and those made by Professors Suzanne Leclercq, Universite without success. The transfer technique of Walton de Liege and Chester A. Arnold, University of Michigan. (1923) was used with limited success and some April, 1957] BECK-TETRAXYLOPTERIS, A NEW DEVONIAN GENUS 351 valuable information about ultimate divisions and branching of the fronds. An excellent series of sporangia was gained. sections was obtained from an r + 1 axis. An DESCRIPTION OF PLANT.-Vegetative portions.­ examination of photographs of two of these sec­ The preserved portions consist of axes considered tions (fig. 19, 20) and the camera lucida drawings to be stems to which are attached complex, radially of the entire series (fig. 21A-H) provides proof symmetrical branch systems of monopodial axes that the r + 2 axes leave the r + 1 axes in nearly with lateral branches of several orders. The branch opposite pairs and that successive pairs are in systems are arranged on the stem in a crowded planes at right angles. Evidence that the ultimate spiral (fig. 1). No expanded blade-like structures divisions also occur in a decussate arrangement recognizable as leaves are present. However, it is is given by these photographs and drawings. not unlikely that these branch systems attached to The decussate arrangement of the r + 1 axes the stem are homologous with leaves. They will on the rachis cannot be fully substantiated by be referred to subsequently as fronds. To facili­ anatomical evidence at present although the cruci­ tate their description the following terminology form shape of the primary xylem strand, identical will be used. The term rachis will designate an with that of the r + 1 axes, is indicative of this axis which usually gives rise to three orders of type of branching. By careful chipping of the lesser axes and which is assumed to be the main compression specimens it becomes quite clear that axis of the frond. The lesser axes will be desig­ all branching within the fronds is opposite or sub­ nated in decreasing order r + 1, r + 2 and ulti­ opposite. mate divisions. These axes branch in an opposite To demonstrate convincingly the radial sym­ or sub-opposite manner (fig. 1-4) with succeeding metry of the fronds on the basis of compressions pairs in planes at right angles. i.e., 4-ranked. Their alone is difficult. On a relatively smooth surface arrangement is therefore quite unlike the spiral of a slab of rock the specimens often appear to be attachment of rachises to the stem. bilaterally symmetrical, but in many cases the . The largest stem fragment found measures about chipping away of successive thin layers of rock 2.5 em. in width and 24 em. in length. There is shows that the radially symmetrical plant has been evidence from both internal anatomy and external greatly compressed by the weight of coarse sedi­ morphology that the stem branched sympodially ment and only appears to be in one plane. When or nearly dichotomously. One axis examined shows such compression has been at a minimum an ir­ a cross-section of the stem at a point of branching regular, diagonal break of the rock exposes the in which there are two large masses of xylem of radial symmetry beautifully. In some cases, even unequal size indicating a pseudomopodial or sym­ on a relatively flat surface, very careful examina­ podial branching. The writer has seen some com­ tion of the angle of departure of pairs of opposite pressed axes in the quarry at Davenport Center axes also gives evidence that they are in alternating which measure up to 8 em. in width and 0.5 m. in planes. This type of evidence cannot unfortunately length. Though it has been impossible to make be illustrated by photographs. any positive identification of these axes it is pos­ On the basis of compression specimens alone sible that they are larger basal portions of the one might assume that all axes of the fronds were stem of the plant under consideration. If so, it is more or less terete. There is good evidence from likely that this plant attained the size of a small anatomical study that the r + 2 axes and the tree as much as 3 m. in height. distal part of the r + 1 axes are distinctly four. Although definite information on the size and lobed, exhibiting a clover-leaf shape in transverse gross structure of the plant is lacking, details of outline as shown diagrammatically in fig. 32. Evi­ the structure of the fronds, both anatomical and dence for this in r + 1 axes is shown in fig. 21C-G morphological, are well known. In overall size in which the v-shaped indentations (drawn as dot­ they attained a length of 30 em. or more and be­ ted lines) represent preserved portions of the epi­ cause of the repeated opposite and decussate dermis which when connected would give a lobed branching they produced a dense, bushy appear­ configuration.