352 EXPLORATIONS ACEOSS THE GREAT BASIN OF UTAH. 



erated, but on well-preserved specimens they present a very beautiful appearance 

 under a lens. Scarcely any marks of growth are visible in most cases. 



From its regularly granulated surface, and some appearance of punctures seen on 

 exfoliated surfaces. 1 am led to suspect that this shell may be a Spiriferina, but I am 

 not sure that it possesses the internal lamina of that type. 



This is a well-marked species, very distinct from all the forms I have seen in any 

 of the Carboniferous rocks of the Western States, and seems not very nearly related 

 to any known foreign species. 



■Locality and position. — Divide between Long and Ruby Valleys. Latitude 40° 

 north, longitude 115° 20' west. From the yellowish limestone series, probably 

 Upper Carboniferous. 



Spirifer (Spiriferina) pulcher, Meek. 



Plate 2, fig. 1, a, b, e, d, e, f, g, h. 

 Spirifvra puhhva. Meek (July, 1860), Proceed. Acad. Nat. Sci. Philad., XII, 310. 



Shell of medium size, more or less compressed, length from one-half to one-third 

 the breadth ; hinge-line equaling the greatest width ; lateral extremities often much 

 extended, compressed, and acutely pointed. Ventral valve more convex than the 

 other in the umbonal region ; beak rather small, and not very strongly incurved ; 

 area somewhat narrow, very slightly arched, or inclined back over the hinge, its 

 margins being subparallel ; foramen triangular, a little higher than wide ; mesial sinus 

 narrow, well defined, rather deep, and smoothly rounded within, extending to the point 

 of the beak, from which it widens very gradually toward the front; lateral slopes on 

 each side of the mesial sinus of the ventral valve, and its corresponding elevation on 

 the dorsal valve, bearing from seven to nine simple, elevated, rather narrowly-rounded 

 plications. Entire surface ornamented by fine, regularly disposed granules, which, on 

 worn or exfoliated specimens, are seen to be connected with punctures; marks of 

 growth moderately distinct, and more or less arched in crossing the plications and 

 mesial fold. 



Length of largest specimen, 1.13 inches; breadth, 3.10 inches; convexity, 0.76 

 inch. 



This is quite easily distinguished from any of its associates, and not very nearly 

 related to any Carboniferous species I have yet seen from other localities. The deli- 

 cate granulations seen on its surface are also well marked on the surfaces of the 

 exfoliated lamina, and are likewise represented by the usual corresponding punctnres on 

 the interior. It varies much in the comparative length of the hinge, though the breadth 

 of the shell is in all cases considerably greater than its length. The individuals having 

 the shortest hinge are also usually more gibbous than the others. 



Internal casts of this shell show that it has the mesial septum of its ventral valve 

 well developed, which, with its distinctly punctate structure, requires its removal to 

 Spiriferina, whether we view that group as a genus or a subgenus. 



Locality and position.— East and west side of Long Valley, and pass east of Ruby 

 Valley. Latitude 40° north, longitude 115° 20' west. Geological position same 

 as last. 



