PEEMO-CAEBONrFEEOtTS PELECYPODA — ETHEEIDGE. 185 



In Fleuropliorus, as described by King, and redescribed by 

 Waagen,* the equi valve closed shell possesses two cardinal inter- 

 locking teeth in each valve, and a posterior lateral one, extending 

 the entire length of the hinge ; there is a lunule and an escutcheon, 

 entire pallial lines, and fairly well marked adductor impressions, 

 the anteriors having before them strong shelly ridges. 



Waagen has pointed out that " one of the two cardinal teeth 

 is often very little developed," and such is the case in most of our 

 specimens, but in a cast in the Geological Survey Collection, the 

 impressions of all four teeth are distinctly visible. 



PlEUROPHORUS GREGARIUS, S/). nov. 



(PI. xxxiii., figs. 2 - 5.) 



Sp. Char. — Shell transversely elongated, oblong, robust, practi 

 cally maintaining the same width throughout its whole length, the 

 latter on an average one and three quarter inches, depth one inch ; 

 dorsal and ventral margins straight, parallel; bodies of the valves 

 convex, most so at about the middle, but the flanks rather flattened 

 or straight walled : faint cinctures exist, cutting the ventral 

 margins at about the centre ; anterior ends small, the margins 

 convexly rounded ; posterior ends but slightly flattened, the 

 margins rounded ; umbones conspicuous and incurved, a little 

 flattened above ; escutcheon long, widening posteriorly; lunule 

 apparently cordiform, shallow ; posterior cardinal teeth below the 

 umbones, the most anterior of the left valve often inconspicuous ; 

 posterior lateral teeth leaving deep impressions in casts, the left 

 often double ; anterior adductor impressions deep, low in position, 

 forming strong prominences in the cast, guarded by a posterior 

 shelly ridge, which varies in intensity in individuals ; posterior 

 adductor impressions faintly marked, continuous; exterio-pallial 

 margins flattened, leaving very conspicuous impressions in casts ; 

 sculpture of concentric laminae, no radii. 



Obs. — With one exception this is only known to me as casts, 

 and in the adult state I find the measurements very constant. 

 The exception referred to, otherwise possessing all the characters 

 of the species, is two and three quarter inches long by one and a 

 half deep. I have only seen one individual that may be P. gregarius 

 with the test preserved, but it is from a diflerent horizon. The 

 sculpture is concentric, with well marked laminae, but without 

 any traces of radiating costae. P. gregarius belongs to the group 

 Imbricati in the classification of Waagen ;t and in outward form 

 resembles to some extent all three species placed by him therein, 

 but is a broader and more robust form. 



* Waagen— Mem. Geol. Surv. India, Pal. Ind. (13), ill., 1881 (Salt 

 Ean?e Fossils, Pelechypoda) p. 214. 

 t Waagen, loc. cit., p. 216. 



BJ 



