NATURAL SCIENCES OF PHILADELPHIA, 309 



in the middle, and without plications. Surface ornamented by from seven to 

 nine depressed, rou^ided, simple, plications on each side of the fold and sinus. 

 Length of hinge about 0*66 inch ; diameter from hinge to front 0*39 inch ; 

 height of area - 26 inch. 



Named in honor of Mr. Henry Engelmann, Geologist of Capt. Simpson's 

 Expedition. 



Locality and position. Neill's Valley, lat. 39 32', long. 115 36'. 



Spieifera macra, Meek. Shell rather under medium size, subtrigonal, or 

 sub-semicircular, considerably wider than long ; hinge line equalling the 

 greatest width, and terminating in rather salient angles. Dorsal valve convex 

 in the middle, compressed towards the lateral extremities ; mesial fold narrow, 

 prominent and angular, especially near the front. Ventral valve more con- 

 vex than the other, sloping somewhat abruptly from the umbo to the sides 

 and front ; mesial sinus narrow, rather deep, with sloping sides, continued to 

 the beak, which is pointed and incurved ; area of moderate breadth, with well 

 defined sloping lateral margins, apparently not continued quite to the extremi- 

 ties of the hinge, arched and inclined back over the cardinal margin ; foramen 

 triangular, higher than wide. Surface of each valve ornamented by about 

 eighteen to twenty-four moderately distinct, more or less bifurcating plications, 

 about six or seven of which usually occupy the mesial fold, and five or six the 

 mesial sinus. Length of hinge, about 1-19 inches ; diameter from hinge to 

 front - 63 inch ; height of area 0.16 inch. 



Locality and position. Same as last. 



CARBONIFEROUS SPECIES. 

 BRACHIOPODA. 



Productus semistriatus, Meek. Shell of medium size, greatest breadth on 

 the hinge line, which is nearly twice the length, measuring from the hinge to 

 the anterior curve. (Dorsal valve unknown.) Ventral valve very gibbous, 

 extremely arched, and greatly produced in front ; sometimes provided with 

 an obscure, very shallow mesial sinus, which never extends to the beak ; ears 

 triangular, strongly vaulted, extended nearly at right angles to the vertical 

 sides of the elevated visceral arch, from which they are each separated by an 

 oblique, undefined sulcus ; beak very convex, distinctly incurved, and ex- 

 tended a little beyond the hinge ; surface of the visceral region marked by 

 small, obscure concentric wrinkles, which are crossed by numerous, more or 

 less bifurcating striae ; anterior half, smooth or only marked by fine lines of 

 growth; spines rather long, erect and scattering. Length of hinge, 1*19 

 inches ; diameter from hinge to anterior curve, 0*72 inch ; length from the 

 beak to the anterior margin of the ventral valve, measuring around its curve, 

 2*14 inches. 



Locality and position. Timpanogos Canon, lat. 40 22', long. 111 38', in 

 dark argillaceous rock. Probably of the age of the Coal measures. 



Productus multistriatus, Meek. Shell above medium size, breadth nearly 

 double the length, from the hinge to the anterior slope ; hinge line longer than 

 the breadth of the shell in front of it ; ears moderately large, triangular, dis- 

 tinctly vaulted, and standing nearly at right angles to the swell of the larger 

 valve. Ventral valve extremely ventricose, strongly arched, and provided 

 with a broad, deep, mesial sinus, extending from the beak to the front ; beak 

 rather small, compressed, and projecting little beyond the hinge. Dorsal 

 valve deeply concave, provided with three broad, obscure, radiating promi- 

 nences, one of which corresponds to the mesial sinus of the other valve, and 

 the other two radiate to the lateral margins in front of the ears. Surface of 

 both valves marked by numerous fine, obscure radiating striae, destitute of 

 spines excepting about three near the extremity of each ear, and some three 

 or four on the anterior slope of the ventral valve. Length of hinge near 1*77 



I860.] 



