DESCHIPTION OF SPECIES. PP. 53 



common at West Union, are almost always fragments of 

 pinnules as in Fig. 8. Tliey have never been seen attached 

 except in a single specimen (Fig. 1) seen at Cassville. 



Habitat — Roof Shales of the Waynesburg Coal, Cassville, 

 and West Union, W. Va. 



Odontopteris pachyderma, Sp. nov., PI. X. Figs. 5-10. 



(Frond, bipinnate ; primary rachis, stont, secondary 

 rachis, slender and delicate ; pinnae, alternate and somewhat 

 closely placed, very deciduous, going off at nearly a right 

 angle ; pinnules, oblong and ovate, inclined forward, some- 

 times falcate, the lowest one on the lower side heteromor- 

 phous, being bilobed, apparently formed of two consoli- 

 dated iDinnules, the lowest ones on the upper side occasion- 

 ally heteromorphous, the lowest pinnules of the lower part 

 of the plant separate nearly or quite to the base, with 

 rounded lobes or undulate on the margins, pinnule of the 

 middle and upper portions united at base, ovate and acute, 

 becoming more united towards the summit of the frond 

 where the pinnae pass into xDinnules, and also toward the 

 end of the xjinnse, being almost entirely united at the ex 

 tremity; leaf-substance, exceedingly thick and dense ; mid- 

 nerve more or less distinct and splitting up dichotomously 

 into branches which diverge in an angular manner ; lateral 

 nerves coming off from the principal rachis also, and branch- 

 ing dichotomoush^, all very delicate, and almost always 

 concealed in the dense parenchyma.) 



The nerves are so fine, and the leaf substance so dense, 

 that out of the large number of specimens examined only 

 one or two showed the details of the nervation. 



The plant usually leaves a dense shining film on the shale. 

 The form of some of the pinnae and pinnules strikingly re- 

 sembles Heer's Pecopteris iriassica, "Pfl. d. Trias u. des 

 Jura," PI. XXV, Figs. 1 and 2, but the nervation is totally 

 different. The singular nervation approaches nearer to that 

 of Odontopteris alpina, Heer. It would come in the sub- 

 genus, O. Mixoneura of Weiss, as would all the species 

 found as yet in the upper beds of West Virginia. 



Habitat— Abundant in the roof shales of the Waynes- 



