NOTES ON THE LEPIDOCARPACEAE 561 



my with it) . The presence of free-sporing megaspores is a character which not 

 only excludes a plant from these genera but also places it beyond the family 

 limits of the Lepidocarpaceae. 



Summary 



Family characteristics of the Lepidocarpaceae are given. It is suggested 

 that Lepidophloios is a possible lepidocarp representative showing the vegeta- 

 tive features of these plants. The diagnostic characteristics of Lepidocarpon are 

 reviewed, and the generic diagnosis is rephrased. The essential distinctions Scott 

 recognized in establishing the genus are entirely valid and should be adhered 

 to rather closely. 



The genera and species discussed include Lepidocarpon lomaxi, the geno- 

 type of the type genus for the family, L. wildianum, and L. westphalicum, all 

 known from English sources. Records of Lepidocarpon in America are reviewed 

 with respect to the characters used in their identification. Points which distin- 

 guish Illiniocarpon from Lepidocarpon are enumerated and the relationship of 

 these genera with the less precisely denned genus Cystosporites is restated. 

 Attention is called to divergent characteristics of Lepidocarpon glabrum from 

 Iowa, and possibly also represented to a lesser degree in another lepidocarp 

 from Harrisburg coal balls, which would seem to set them apart from the 

 genus Lepidocarpon. Reasons are given for referring the American forms 

 named Cantheliophorus to Lepidocarpon. 



American lepidocarps in particular are worthy of intensive study because 

 the diversified forms present a particularly interesting problem of plant evolu- 

 tion. In the following tabulation of the Lepidocarpaceae each species is listed 

 according to its approximate age. The larger number of forms occurring in 

 post-Pottsville beds supports the conclusion that diversification was more rapid 

 during that time. 



Post-Pottsville (Post-Westphalian B) 



Lepidocarpon mazonense Schopf Illiniocarpon cadyi Schopf 



L. corticosum (Lesq.) Cystosporites breretonensis Schopf 



L. novaculeaium (Bassler) C. giganteus (Zerndt) 



L. robustum (Bassler) Lepidocarpon lomaxi (?) 

 L. subulatum (Bassler) (Noe, Krick, Fisher & Noe) 



L. linearifolium (Lesq.) L. sp. Reed 



L. sicatum (Bassler) — L. (?) glabrum Darrah 

 (also in upper Pottsville) 



Pottsville 

 (Mid-Lanarkian to Staffordian ; Mid-Namurian to Westphalian C) 



Lepidocarpon Tvestphalicum Kidston Lepidocarpon grande (Bassler) 



L. lomaxi Scott L. ensiferum (Bassler) 



L. Toaldenburgense (Potonie) L. pugiatum (Bassler) 



Cystosporites giganteus (Zerndt) L. ioroense Hoskins & Cross 



(of Pottsville age*) 



* For description see Amer. Midi. Nat. 25(3) :543, 1941. (Horizon information 

 fide Cross June 9, 1941.) 



