10 



PALEOZOIC FOSSIL SPORES 



the further difficulty that no simple correct 

 morphological designation can be applied 

 similarly to the dispersal forms of the 

 male gametophyte bodies in both modern 

 and fossil forms. The dispersal stage 

 rather than the degree of gametophytic 

 development is of greatest practical signifi- 

 cance when fossils are considered. The 

 terms perispore, exospore, and endospore 

 might seem equivalent to the pollen struc- 

 tures perine, exine, and intine, respec- 

 tively. However, in the case of the bladder- 

 equipped fossil gymnospermic pollen, 

 the bladder membrane which seems very 

 similar in morphologic character to the 

 perisporal membrane of certain crypto- 

 gamic forms, is regarded by many as 

 equivalent to the exine of angiospermic 

 pollen. 



Revision of the morphologic termi- 

 nology for fossil spores and similar micro- 

 fossils also seems required. Not only has 

 there been a dearth of descriptive terms 

 available for description of the varied 

 structural features, but a good many deep- 

 ly rooted terms have become outmoded. 

 Several of these date from the period in 

 which Selaginella was presented as a 

 primitive forerunner of modern seed 

 plants, and their homologous implications 

 now oftentimes seem unwarranted. Non- 

 commital descriptive terms, which seem 

 reasonably free ^of theoretical connota- 

 tions, have been preferred for use in the 

 present paper. It is hoped that it will be 

 possible later to treat the descriptive 

 morphology of spore forms specifically 

 in greater detail. 



In the synoptic lists the species assigned 

 to each genus are given in alphabetical 

 order. The order of genera adopted is 

 chronologic according to the time each 

 was first proposed. Although some inter- 

 generic alliances can be recognized now, 

 and a more logical sequence should be 

 adopted in later works, it is felt that 

 the chronologic order of priority will be 

 of some convenience for taxonomic refer- 

 ence. 



Nearly all the references cited (p. 62) 

 are those of particular taxonomic or mor- 

 phologic pertinence for the fossils dis- 

 cussed. Although we believe this repre- 

 sents a reasonably complete survey of this 

 literature, it does not include all articles 



that deal incidentally with Paleozoic 

 spores. Various non-taxonomic systems 

 have been used by some workers in desig- 

 nating types of spores in coal thin- 

 sections, notably by Slater and his col- 

 leagues in the South Yorkshire laboratory 

 of the British Fuel Research Division, 

 by Th. Lang in Silesia and, most impor- 

 tantly, by Reinhardt Thiessen. These 

 apply very slightly to the present work 

 because species cannot be as reliably dis- 

 tinguished from spores in thin-sections, 

 the significant biological characters are 

 generally more difficult to ascertain, and 

 the informal nomenclature used does not 

 require systematic consideration. Con- 

 sequently articles of this nature are not 

 considered except in connection with the 

 morphology of certain forms. 



On the other hand, there is a consider- 

 able literature on isolated spores in the 

 Russian language which needs to be given 

 careful study before nomenclatorial stabil- 

 ity can justifiably be hoped for. Thus far 

 only a small portion of this literature has 

 been available to us, chiefly in abstract 

 form, and this is insufficient to provide 

 a satisfactory basis for understanding the 

 quite different nomenclature Russian 

 writers have used. Naumova (1937) 

 mentions that about 400 species have been 

 distinguished based on material ranging 

 in age from the Lower Carboniferous to 

 Tertiary. He mentions genera designated 

 as Zonotriletes and Azonotriletes. Nikitin 

 (1934) has distinguished the genus Kry- 

 shtofovichia based on very singular ap- 

 pearing, large spores of Devonian age. 

 Luber (1938) mentions subgroups (gen- 

 era?) Azonotriletes, Zonotriletes, Azono- 

 Jiionoletes, Azonaletes and Zonaletes and 

 distinguishes several apparently valid 

 species. In a more recent publication 

 Luber (1939) uses the generic ( ?) names 

 PlaguUtes, Turriella, Circelliella, Saccri- 

 inalia, Circella, Libumella, Spinosella, Sub- 

 sac culifer and Plicatella. It is to be hoped 

 that under more favorable circumstances 

 it will be possible to give full consideration 

 to the Russian studies which have already 

 been put to good use in the age determina- 

 tion and correlation of the widely sep- 

 arated coal deposits of the USSR and to 

 integrate the nomenclature they are using 

 with our own. 



