229 



Lima. 



spathulata. . oblongo-ovate, depressed upwards, rays squamalous, 

 hinge straight. . Grignon. 



mutica. . ovate, oblique, inequilateral, both sides gaping, rays 

 smooth, rather sharp. 



plicata. . ovate, inequilateral, subtruncated forwards ; rays 

 plicaeform, obtuse, rather smooth, obsoletely squamous. . 

 Touraine. 



vitrea. . oblong, thin, pellucid, depressed, hinge oblique. . 

 Grignon. 



dilatata. . roundedly ovate, oblique, depressed, rays thin, obso- 

 lete, distant. 



Plagiostoma. 



transversa. . large, transversely ovate, upper part rounded ; 

 lower sides oblique ; numerous longitudinal grooves trans- 

 versely striated. . 6 inches wide. 



" semilunaris. . large, trigonal, smooth, very wide on the foreside, 

 semicircular, with a sharp edge, hinder side truncated, 

 thick, subconcave, one-eared. . Calvades. 



turgida. . longitudinally grooved, upper valve with sharp serru- 

 lated grooves ; the other with smooth and obtuse ones. . 

 Chateau de Loir. 



depressa. . suborbicular, lower part rather thin, upper rounded, 

 small longitudinal striae divaricating to the side. 



sulcata. . ovate, lower part subacute, longitudinally radiiform, 

 subcarinated grooves. 



inequivalvis. . upper valve flat, longitudinally striated ; near the 

 border rough with vaulted squamulae. . Bourdeaux. 



Pecten. 



solarium. . suborbicular ; rather convex on both sides ; rays 

 fifteen or eighteen, distinct, flat, scarcely any longitudinal 

 striae. . Doue. 



multiradiatus. . convex on both sides ; eighteen to twenty rays, 

 distinct, convex, and smooth. 



rugosus. . convex on both sides ; fourteen to eighteen convex 

 rays ; transversely rugose. . Normandy. 



laticostatus. . suborbicular, large, convex on both sides ; seven 

 to ten flat, very broad, faint, rays ; grooves longitudinal, 

 obsolete. 

 The largest pecten known. . 8 inches wide. 



rotundatus. . subordicular, convex on both sides ; fourteen to 

 sixteen distinct convex rays, flat towards the circum- 

 ference. . Vence. 



lurdigalense. . suborbicular, very wide, convex, radiated on 

 both sides, from twelve to fourteen convex rays, becoming 

 flat towards the circumference. . 5| inches. 



aculicosta. . suborbicular, rather convex on both sides, with 

 twenty-one rays on the back ; acute and smooth. . 2| 

 inches. 



