CARBONIFEROUS SPECIES. 85, 



beak rather distinctly incurved and but very little projecting; lateral slopes 

 costate as in the other valve. Surface of both valves with a few rather 

 strong zigzag marks of growth, most distinct near the deeply interlocking, 

 angular serratures of the anterior lateral margins, showing very clearly, 

 under a common single lens, the rather large punctures regularly arranged 

 in quincunx. 



Length, measuring from the most prominent part of the ventral umbo 

 to the front of the mesial fold of the dorsal valve, 0.82 inch; breadth, about 

 0.93 inch; convexity, 0.68 inch. 



This shell seems to be related to a common form in our western Coal- 

 Measures, generally known in this country by Dr. Shumard's name S. Ken- 

 tucJcemis (but supposed by Mr. Davidson not to differ from S. octoplicata of 

 Sowerby), though it is probably distinct from Dr. Shumard's species. With- 

 out more and better specimens for comparison, however, I scarcely feel war- 

 ranted in regarding it as new. The only individual of it in the collection 

 has the lateral extremities broken away, but it is evidently a larger and more 

 robust and more gibbous shell than any specimens of the form described by 

 Dr. Shumard that I have seen, and differs both from that and the European 

 typical S. octoplicata in having its mesial fold much more elevated, and pro- 

 jecting forward so as to impart a very distinctly angular outline to the middle 

 of the anterior margin. Should other specimens show these characters to 

 be constant, I should think it entitled to a distinct name, either as a species 

 or as a variety, and would in that case propose to call it 8. gonionota, in 

 allusion to its high angular mesial fold. 



Locality and position. — Light-colored limestone of Carboniferous age at 

 Railroad Canon, Diamond Mountains, Nevada. 



Spiriperina pulchra, Meek. 



Plate 8, figs. 1,1 a, h, c, d, e; and pi. 12, figs. 12, 12 a, b, c, d?. 



Spirifera pulchra,, Meek (1860), Proceed. Acad. Nat. Sci. Philad., XII, 310; and (1876) 

 in Col. Simpson's Report of Expl. across the Great Basin of Utah, 352, pi. 2, 

 figs. 1 a and 1 h. 



8piri/erma pulchra, Meek (1865), Palseont. Upper Missouri, 19. 



Shell of about medium size, transverse, rather compressed, or some- 

 times gibbous ; breadth from twice to about three times the length ; lateral 



