CARBONIFEROUS SPECIES. 93 



by a typograpliical error, printed Lindkardia). As stated in the foregoing- 

 remarks, the specimens examined by me are flattened between the laminse 

 of shale, and therefore in a very unfavorable condition for satisfactory 

 generic determination. I have not seen them since writing the foregoing 

 description, six years back ; and the old work in which Miinster described 

 the genus LunuUcardium is one of tlie very few publications of the kind 

 that I have never yet been able to consult. If I am correctly informed, 

 the hinge of LunuUcardium is unknown, and it is very improbable that any 

 specimens of the shell here under consideration showing the hinge have yet 

 been found. From the impressions of its general physiognomy, however, 

 left on my mind, it would seem to differ much from the general external 

 characters of LunuUcardium excrescens, Miinster, which is the species gen- 

 erally figured as an illustrative example of the genus. That it is certainly 

 a Posidonomya, however, I have never asserted.] 



LocaUty and jjosition. — White Pine Mountains near Hamilton, Nevada; 

 from a black laminated shale of Devonian or Carljoniferous age. 



Genus AVICULOPECTEN, McCoy. 



AvicuLOPECTEN CAT ACTUS, Meek. 

 Plate 3, figs. 10, 10 a (and 10 b ?). 



Shell rather under medium size, much compressed, very thin and hav- 

 ing scarcely any degree of obliquity — exclusive of the ears, subovate in 

 outline ; hinge-margin less than the greatest breadth ; posterior and anterior 

 margins rounding into the regularly-rounded base. Left valve compressed- 

 convex ; ears nearly flat ; the posterior one not distinctly separated from 

 the swell of the umbo, about as long as the margin below, from which it is 

 separated by a broad, more or less rounded, moderately deep sinus, which 

 imparts a rather acute angularity to its posterior extremity ; anterior ear a 

 little declining, with its anterior margin slightly convex in outline, but ter- 

 minating nearly in a right angle above, and defined below by a rather shal- 

 low, obtusely angular sinus ; beak slightly nearer the anterior side, project- 

 ing a little above the hinge, and inciu-ved, but not oblique. Right valve 

 nearly flat, and having the same general outline as the other, excepting 

 that its beak is much less distinct from the hinge-margin, and the sinua 



