44 FLORA OF LOWER COAL MEASURES OF MISSOURI. 



in the latter. The position of the pinnae on the right in this specimen indi- 

 cates a point of origin beneath the surface of the rachis as here presented, 

 which probabl}" consists of a central axis with thick lateral laminae. The 

 pinna? probably spring from the central axis. 



Splienopteris missouriensis is perhaps most closely related to the S. tenu- 

 ifolia Brongn./ from which it differs by the more open angle of the pinna?, 

 which are less acute, and the closer pinnules or lobes, which seem to be more 

 broadly cuneate, with more obtusely rounded teeth. It also resembles, 

 somewhat the specimens figured by Stur^ as Saccopteris grypophylla (Goepp.) 

 Stur, or as Sphenopteris forniosa by Achepohl,' thoiigh these species differ in 

 the details as much as in size. 



I am far from certain that the fragments which I have described as 

 Sphenopteris Broacllieadi are not really the fertile pinnae of 8. missouriensis. 

 I have separated them, however, on account of the more slender, distant, 

 acute pinnae, and the more oblique and much more deeply dissected pinnules 

 and lobes which remain simple or only bifid to a much larg-er size than in 

 the latter species. While it is possible that the fertile pinnae represent only 

 modified and somewhat reduced pinnae, of the sterile species, it hardly seems 

 probable that in such a case the individual ultimate divisions would retain 

 the common characters to a greater size while presenting a simpler form of 

 division combined with a greater degree of dissection. The force of this 

 will be seen in a comparison of the fertile pinnae with the smaller sterile 

 fragment, Fig. 2, PI. XIV, which probably comes from the upper part of a 

 frond of the same species as the large fragment. Both the fertile and the 

 sterile forms have probably a relation to the Cheilantliites (^Sphenopteris) 

 grypophyUa Goepp. 



The heteromorphous pinna seen at the base of the lower lateral pinna 

 on the right in the large specimen is suggestive of a relationship for our 

 species to the genus Diplothnema Stur. The form of the large fragment 

 illustrated is, however, opposed to such a consideration. 



Localities. — Pitcher's coal bank, U. S. Nat. Mus., 5663 ; Hobbs's coal 

 bank, U. S. Nat. Mus., 5664. 



'Hist. V(Sg. foss., p. 190. pi. xlviii, figs. 1, la. 

 = Farne d. Carbon-Florn, pi. liii, fig. n. 

 ^Niederrb.-Westfiil. Steiukohleugeb., pi. xiv, tig. 8, p. 51. 



