20 



ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 463 



teris , Ptychocarpus and Cyathotracus . The generic determination can therefore 

 be reached only through the specific determination. This can be a quite mislead- 

 ing way, especially if the veins and the outline of the lamina are as indistinct 

 as in these fertile specimens. 



The difficulty in distinguishing among some of the above genera has led 

 to an extended discussion in the literature. Hirmer (1927) and Barthel (1970) con- 

 sidered Asterotheca synonymous with Scolecopteris . Mamay (1950) pointed out 

 the discrepancy between the occurrences of the two genera: Scolecopteris is found 

 mainly in coal balls and Asterotheca only as compressions. A similar discrepancy 

 exists between Cyathotrachus (only in coal balls) and Ptychocarpus (mainly as 

 compressions), which may be congeneric. 



Spores in situ of approximately 70 species of Marattiaceae fructifications 

 have been described in the literature (Watson, 1906; Scott, 1932; Andrews, 1943; 

 Moore, 1946; Mamay, 1950; Remy and Remy, 1955, 1957; Doubinger, 1961; Ewart, 

 1961; Potonie, 1962, 1965, 1967; Brush and Barghoorn, 1964; Barthel, 1967; 

 Laveine, 1969, 1970). The spores vary from monolete to trilete with a short third 

 ray to trilete; from laevigate to granulose to verrucose with irregular thickening of 

 the exine (as in Torispora) ; and from about 10 u.m to at least 124 u.m in diameter. 

 A discussion of each of these taxa is beyond the scope of this paper. Recently 

 Laveine (1970, p. 288-296) has discussed the paleobotanical implications of 

 using spore morphology in an attempt to verify natural relationships among species 

 of the form-genus Pecopteris . Table 4 shows that there is no direct correlation 

 between the form of the spores and several genera (Asterotheca , Scolecopteris, 

 Ptychocarpus ) . Generalizations are possible for Danaeites (monolete, granulate, 

 Laveine, 1970), Acitheca (only trilete; granulate or verrucose), Eoangiopteris 

 (trilete, reticulate) and Cyathotrachus (monolete, laevigate). The lack of cor- 

 relation in the larger genera may be natural, but it is also possible that this 

 points out our lack of understanding of natural relationship in those groups. 



The specimens studied here can be placed into three distinct groups ac- 

 cording to the spores. Spores: 



(1) monolete, bean-shaped, granulose, small (about 10 x 20 u.m); 



(2) trilete with one short ray, round, granulose, small (about 18 u.m); 



(3) trilete, round, granulose, large (about 50 jim) . 



TABLE k - DISTRIBUTION OF FORMS OF SPORES OF CARBONIFEROUS MARATTIACEAE 

 (FROM VARIOUS SOURCES CITED IN TEXT). A = ASTEROTHECA, Ac = ACITHECA, 

 C = CYATHOTRACHUS, D = DANAEITES, E = EOANGIOPTERIS, P = PTYCHOCARPUS, 



S = SCOLECOPTERIS 





Trilete 



Monolete 



number 



of 

 species 



genera 



number 



of 

 species 



genera 



smooth or punctate 



granulate 



verrucose 



reticulate 



conate 



cristate 



10 S + A + P 19 A+S + C + P 

 12 A + Ac 18 A + D + P 

 1 Ac 1 S 

 3 E + S — — 



— — 2 A 



— — 1 A 



