NOTES ON THE LEPIDOCARPACEAE 555 



the distinction between the two genera. The individual sporophylls (not cones) 

 of Illiniocarpon are properly described as pedunculate, and by modification of 

 the pedicel and other changes these plants have lost the strobilar habit of 

 fructification to a significant degree. The integumentary organ (which, as Scoct 

 emphasized, is not merely the upturned margin of sporophyll lamina) is more 

 specialized, and the actual lamina is extended, broad, and doubtless served as 

 a wing for dispersal of the fruit after it had been shed as a unit from the 

 fertile branch. The laminae of some Lepidocarpon species also probably served 

 this same function [e.g., L. mazonense, (?) L. linearifolium (Bassler)] and 

 thir- may perhaps be regarded as a miner example of evolutionary parallelism 

 in the two groups. 



Numerous large fibrous sack-like bodies (seed megaspores) with trilete 

 appartus at one end similar to those Zerndt (1930) described as Triletes 

 giganteus have been obtained by the writer from maceration residues of coal. 

 These seed megaspores are closely related to Lepidocarpon mazonense but 

 because essential diagnostic characters can not be established and because these 

 isolated seed megaspores appeared to be moderately generalized, it has seemed 

 unwarranted to identify them with either of the two genera that had been 

 previously recognized in the Lepidocarpaceae. Their characters, however, fully 

 supported their reference to this family, and the genus Cystosporites was 

 proposed for their reception (S'chopf, 1938b). This genus maybe entirely or 

 only in part equivalent to the Lepidocarpaceae but it clearly exceeds the scope 

 of other genera more adequately diagnosed on the basis of their sporophyll 

 structure. Biologically it appears to overlap both of the established genera, and 

 the isolated spores are thus classifiable with less precision thin is possible 

 where complete fruits are available, but for scientific reporting a name is none 

 the less essential for them. It is incorrect to assume that Cystoporites is 

 only the seed megaspore of Lepidocarpon (Darrah 1941, p. 89), because its 

 relationship is definitely broader. The significant contribution aJorded by the 

 recognition of Cystosporites is that it shows best how geologically long lived 

 and widespread the Lepidocarpaceae were in Carboniferous times (cf. Schopf 

 1938b; Zerndt, 1937, p. 68; 1940, p. 142). Not only is Cystoporites a practi- 

 cal generic designation of use in classification of these isolated seed megaspores, 

 but it also indicates a group of natural affinity and certain bioogical signifi- 

 cance. The delimitation of its natural affinity is in fact far more precise than a 

 great many other generic groups commonly used in the ckssificition of fossil 

 plants. It should be recognized that the introduction of such a genus is not a 

 "purely artificial method of classification" and that plants which have been 

 classified as Cystosporites do not already possess any other properly assignable 

 generic names. 



In 1938 the writer discovered that the holotype of Carpolithes corticosus 

 Lesquereux is clearly cospecific with a form previously discovered in the 

 Mazon shale which he had interpreted as a variant of L. nazoiense. Further 

 study showed conclusively that Lesquereux' species was quite dstinct from L. 

 mazonense. Later, when Janssen's treatise on certain of the Lsquereux types 

 war in preparation, the writer was invited to contribute a revisim of this form, 



