74 PP. REPOET OF PROGRESS. FONTAIuS^E & WHITE. 



V shaped figure ; in tlie lowest portion of the frond one 

 branch again divides before reaching the margin.) 



Tliis plant varies a good deal in appearance according to 

 the portion of the frond from which the specimen comes. It 

 . has always a peculiar rigid asx:)ect. It is allied to P. oreop- 

 teridla, Brongt., but differs in the broad lateral nerves and 

 their peculiar mode of diverging from the midnerve, and in 

 the more gradual passage of pinnae into pinnules toward 

 the summit of the frond. 



Figs. 6, 6a, 65, PI. XXVIII, show normal and magnified 

 forms of a i)inna and pinnules from the lower portion of 

 the frond where the pinnules are larger and have the lateral 

 nerves more complex than in the usual form. PI. 18, Fig. 

 25, shows the peculiar flat lateral nerves as seen under a lens 

 when they are shown to consist of two consolidated bundles 

 of nerves instead of one, as is usually the case in these lat- 

 eral nerves. These two fibres, closely placed side by side, 

 give the nerves their broad character. Fig. 1, PI. 18, repre- 

 sents a segment of the middle portion of a primary pinna ; 

 Fig. 2 of the same plate a portion nearer the end, and Pigs. 

 4 and 5 the extremity of the same pinna. Fig. 3 is probably 

 a primary pinna near the summit of the frond. 



The distribution of this plant is somewhat i^eculiar. At 

 Cassville it is confined to the seam of shale which separates 

 the highest layer of coal from the main mass, and has not 

 certainly been seen above or below this 12 inch bed of shale. 

 It occurs nowhere else, apparently, in the Upper Measures, 

 but is found here in immense quantities. 



Habitat. — Roof shales of the Waynesburg Coal, Cassville, 

 West Virginia. 



Pecopteris rotundiloba^ Sp, nov., PI. XVII, Fig. 2. 



(Frond, tripinnate ; primary rachis rather thick ; second- 

 ary pinnae, going off at an acute angle with a slender rachis ; 

 pinnules alternate linear with rounded lobes ; primarj^ nerve 

 rather strong, and divided into nervules towards the end ; 

 nerves of the lobes mostly simple, and going off acutely 

 from a well marked midnerve. In the terminal lobe, wliich 

 is the largest, the midnerve divides dichotomously.) 



