52 ' FLORA OF LOWER COAL MEASURES OF MISSOURL 



upward, obtuse, entire, or slightly crenulate before becoming pinnatifid, a 

 little decurrent and narrowly connate; lamina thin, dull, arched gently 

 backward toward the margin; nervation quite distinct, clear on the upper 

 siirface of the pinnule, in relief on the lower surface ; primary nerve oblique 

 or slightly decurrent in the lower part, which is much nearer to the inferior 

 than to the superior angle of the pinnule, thin, though sometimes appearing 

 double on the lower side of the lamina, slightly geniculate at the bases of 

 the nervils, and passing to near the apex of the pinnule; nervils rather 

 distant, oblique, at a variable angle of divergence, simple and straight in the 

 upper part of the rather small pinnules, generally forking once below the 

 midrib, and, in the larger pinnules, the upper branch usually forking again. 



The specimens representing this species are quite uniform in their 

 characters, the most conspicuous of which are the form, compactness, size, 

 and entireuess of the pinnules, and the distinctness, thinness, and distance 

 of the nervation. 



Fragments of the pinnae might, at first glance, be taken for some form 

 of Pecopteris, e. g., P. dintoni Lx., on account of the resemblance in the size 

 and outline of the larger pinnules and isolated ultimate pinnae. The mode 

 of division and the other features of the rachis, which is here and there 

 marked by punctation, and the nervation are, however, those of Sphenopteris. 



The relation of this species is with the group repi'eseuted by Splienop- 

 teris cristata Brongn. and S. climropliyUoides Brongn., the nervation of which 

 is plainly similar. In a few instances, where the backward-arched margin 

 is broken or buried in the matrix so as to render the pinnules more pointed 

 with rough borders, the resemblance to some of the American specimens 

 listed as S. chmrophyUoides is especially strong, and it is not impossible that 

 our plant may have been in certain cases identified as that species. 



Splienopteris siispecta is readily distinguished from 8. clicerophylloides 

 Brongn. and 8. cristata Brongn. by its more broadly ovate, obtuse pinnules 

 with entire margins. The nervation differs much from 8. Integra Andi-ji, 

 while the margins, thin lamina, and more slender character of the pinnae 

 preclude any confusion with partially covered fragments of 8. Brittsii Lx. 



Localities. — Owens's coal mine, U. S. Nat. Mus., 5650, 5651, 5652 ; 

 Pitcher's coal mine, U. S. Nat. Mus., 5649, with Cordaites communis Lx. 

 and Hysterites Cordaitis Grr. 'E'y. 



