30 PROCEEDINGS OF THE GEOLOGICAL SOCIElT. [NoV. 20, 



13. Camaeophoria Purdoni, Dav. PI. II. fig. 4. 



Shell somewhat obscurely subrhomboidal or deltoid, wider than 

 long. Yalves almost equally convex, with a wide mesial fold of 

 moderate elevation in the dorsal valve, and a corresponding sinus in 

 the ventral one. The surface of each valve is ornamented with from 

 eighteen to twenty-two angular ribs, of which from seven to eight 

 occupy the fold, and from six to seven the sinus. The beak is small 

 and much incurved ; so that the foramen, which is situated under 

 the angular extremity of the beak, is but slightly seen. No marginal 

 expansions could be perceived. 



This species does not appear to be rare in the Punjab; it occurs at 

 Moosakhail, Yurcha, &c. 



14. Streptorhtnchus Crenistria, Phillips, sp. 



Some very large examples, which entirely agree with our British 

 specimens, have been found at Moosakhail, at Yurcha, and in other 

 localities ; one in particular measured nearly 4 inches in length by 

 about 5 in width and IJ in depth. The specimens are usually very 

 irregiilar in their shape, from contortion and malformation, but agree 

 in all their characters with Phillips's type. 



15. Streptorhtnchtjs Crenistria (Phillips), var. robusttjs, Hall. 



PI. I. fig. 16. 



Oi'tMs rohusta, Hall, Report of the Geological Survey of the State 

 of Iowa, p. 713, pi. 28. fig. 3 ; 1858. 



Shell somewhat marginally pentagonal and plano-convex ; hinge- 

 line nearly as long as the width of the shell. Dorsal valve semi- 

 circular and gibbous: ventral valve pentagonal and nearly flat; 

 area triangular and wide, with a narrow pseudo-deltidium. Surface 

 marked by small radiating striae with interspaces of almost equal 

 width, while at variable distances from the beak finer interpolated 

 strioe occur between the larger ones. The valves are also crossed by 

 numerous concentric lines or striae. A specimen from the Carboni- 

 ferous Limestone of Yurcha measured 21 lines in length by 23 in 

 breadth and 14 in depth. 



The Punjab examples of this variety of S. Crenistna so closely re- 

 semble a specimen of Orthis rohusta, Hall, from the Lower Coal- 

 measures of St. Clair County, lUinois, in North America, that I am 

 induced to consider them identical. 



IG. SrREPTORHYNcnTJs pectinipormis, Dav. PL I. fig. 17. 



Slicll scallop-shaped; valves equally convex ; hinge-line sometimes 

 less, rarely longer, than half the width of the shell, with projecting 

 angular extremities. Yentral area triangular, usually higher than 

 wide, and longitudinally divided by a narrow convex pseudo-delti- 

 dium. The beak is pointed and tapering at its extremity, which is 

 generally bent or twisted more to one than the other side. Dorsal 

 valve pcctcn-shapcd, very convex at the umbonc, with small cared 

 expansions, this valve being also slightly depressed along the middle. 



