FEENS— TEIPHTLLOPTEEIDE.13— EREMOPTERIS. 1 7 



niculate, sleuder, flat or canaliculate above, round-terete beneath, lineate, 

 bordered on either side by a rugose-lineate lamina nearly equaling the axis 

 in width; ]3rimary pinnse not very large, palmate above the very open- 

 angled dichotomies; secondary pinnae ovate, deltoid, or triangular, rather 

 dense, often slightl}^ geniculate toward the base to suit the origiii of the 

 tertiary pinnae; tertiary pinnaj alternate, open, the lower at a right angle 

 to the axis or slightly reflexed, the basal ones shorter, close, often slightly 

 overlapping-, often flexuous, linear-triangular, acute; pinnules or inferior 

 divisions open near the base, oblique farther up, sometimes a little distant, 

 but generally close or partly overlapping, alternate, variable in size, more 

 or less broadly ovate or triangular, the basal ones palmate, more or less 

 deeply cut in subdivisions or lobes, decurrently alate; lobes or ultimate 

 divisions linear, obcuneate or somewhat narrowly obovate, deciuTent, 

 obtusely pointed, obtuse, often truucate-emarginate or shallowl}- bifid at 

 the apex; nervation thin, often obscured; jirimary nerve decurrent, fork- 

 ing near the base to supply each division, or again at the base of each lobe, 

 a single nervil entering into and passing to the apex of eacli lobe or tooth; 

 lamina moderately thick, rugose, with fine, short bristles or very naiTow 

 scales appressed parallel to the nervation. 



This species, represented by a large suite of specimens, shows consid- 

 erable variation in the outlines of the iiltimate pinnae or pinnules, according 

 to their position in the frond and the degree of their development. Some- 

 times the lower basal pinnules in the lower part of the frond present a 

 form resembling Sphenopteris spinosa, while those near the end of the upper 

 pinnse approach Sphenopteris furcata ; and, in fact, an examination of the 

 specimen on which the record^ of the occurrence of the latter species in tliis 

 region appears to be based, shows clearly that it is a part of the marginal 

 portion of a frond of Eremopteris missouriensis. I have seen precisely the 

 sarne form on a rock in direct union with the normal form of the Missouri 

 species. Moreover, I am unable to find any distinctive characters by wluch 

 specimens from this region labeled Splieiiox)teris spinosa Groej^p. and Sphe- 

 nopteris splendens by Lesquereux can be even varietally separated from the 

 fine series of examples of Eremopteris missouriensis. 



The original desci'iption and illustration of Eremopteris missouriensis, 



' Coal Flora, toI. lii, p. 880. 

 MON XXXVII 2 



