310 PROCEEDINGS OP THE ACADEMY OF 



inches ; length from hinge to anterior slope 1 inch ; greatest breadth in front 

 of the hinge l - 48 inches. 



Locality and position. Yellowish limestone series, east side of Long Valley, 

 lat. 39 Q 57' north, long. 115 10' west. Probably of upper carboniferous age. 



Spikifera scobina, Meek. Shell rather large, subcircular, approaching sub- 

 pentagonal, moderately gibbous, length and breadth nearly equal, hinge line 

 scarcely equalling the greatest breadth ; lateral margins rounding anteriorly 

 and intersecting the hinge almost at right angles. Valves nearly equally 

 convex, each provided with from about seventeen to twenty-two, rather 

 broad, depressed, occasionally bifurcating plications. Ventral valve a little 

 more gibbous than the other, and having a shallow mesial sinus, which is very 

 small near the beak, but widens gradually towards the front ; beak moderate- 

 ly prominent, incurved; area of medium breadth, with nearly parallel margins, 

 extending to the lateral extremities of the hinge, distinctly arched near the 

 beak ; foramen having nearly the form of an equilateral triangle. Dorsal valve 

 moderately convex in the umbonal region ; beak rather prominent and 

 incurved ; mesial fold depressed, not distinctly defined excepting at the front, 

 where it is generally flattened. Surface of both valves apparently without 

 striae, but beautifully ornamented by numerous minute regularly disposed 

 granules. Breadth 2 inches ; length 1*88 inches ; convexity l - 34 inches. 



Locality and position. Divide between Long and Ruby Valleys, lat. 40 

 north; long. 115 c 20' west, from the yellowish limestone series. Probably 

 upper carboniferous. 



Spikifera pulchra, Meek. Shell of medium size, more or less compressed, 

 length from one half to to one third the breadth ; hinge line equalling 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 sub-parallel ; foramen triangular, a little higher than wide ; mesial sinus 

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

 the point of the beak, from which it widens very gradually towards the front. 

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

 elevation on the dorsal valve, there are from seven to nine, simple, elevated, 

 rather sharply rounded plications. Entire surface ornamented by fine regu- 

 larly disposed punctae and moderately distinct marks of growth, which latter 

 arch in crossing the plications and mesial fold. Length of largest specimen 

 1*13 inches ; breadth 3"10 inches ; convexity 0.76 inch. 



Locality and position. East and west side of Long Valley, and Pass east of 

 Ruby Valley, lat. 40 north, long. 115 20' west. Geological position same as 

 last. 



CONCHIFERA. 



Pecten Utahensis, Meek. Shell of medium size, thin sub-circular, much 

 compressed, apparently nearly equivalve, the left valve being slightly more 

 convex than the other ; ears small, subequal, triangular, and distinctly flat- 

 tened ; posterior ear truncate nearly at right angles to the hinge, sometimes a 

 little rounded on the truncate edge ; anterior ear separated from the margin 

 by a very shallow sinus ; surface of the left valve ornamented by rather 

 obscure, unequal, depressed, radiating costae, and numerous, extremely fine, 

 equidistant, thread-like, concentric lines, scarcely visible without the aid of a 

 lens ; right valve smooth, or only marked by fine concentric striae. Length 

 about 1-10 inches ; breadth 1*20 inches ; length of hinge 0.57 inch. 



Locality and position. Summit Spring Pass, divided between Long and 

 Ruby Valleys, lat. 39 33', long. 115 12' west. Probably upper carboniferous. 



CEPHALOPODA. 



Ortaoceras baculum, Meek. Shell rather small, elongate conical ; section 



[July, 



