BIVALVIA. 35 
squamatis, intervallis, triplolatioribus ; costis extremis minoribus ; auriculis subequalibus, 
transverse lamellosis. Valva dextra convexiori quinquesulcata, concentrice tenuiter lamellosa ; 
sulcis concavis, costis altere valve respondentibus ; costis latioribus convexis, subdivisis. 
(Buvignier.) 
Shell suborbicular, inequivalve, depressed. The left valve nearly flat, with fine radiating 
ribs, separated by very wide intervals ; the costae have large, squamous plications, rather 
irregular, and nearly disappearing as they approach the apex, the coste near to the margins 
being the smaller ; the intervals between the costa have five regular, concentric, squamous 
plications ; the auricles are nearly equal, they are transversely lamellated. The right 
valve is convex, with five radiating sulcations, corresponding to the five costs of the other 
valve ; the whole surface of the valve is covered with delicate, regular, concentric, closely 
arranged lamella. The interior of the valves present an appearance corresponding with 
the ornamentation of the exterior. 
Height rather greater than the breadth, and thrice the diameter through both the valves. 
Geological Position and Locality. The Cornbrash of Scarborough and of Northampton- 
shire ; the collections of Mr. Leckenby and of the Rev. A. W. Griesbach contain fine 
specimens. M. Buvigmier quotes the species from the lower ferruginous beds of the Oxford 
Clay, Ardennes and Meuse. 
Hinnites Grapus, Bean, sp. Tab. XXXIII, figs. 10, 10a. 
PrcTEN GrabDus, Bean. Mag. Nat. Hist., 1839, 
Testa valva sinistra, ovato orbiculari convexo-plana, radiatim undulato costata et con- 
centrice lineata ; umboni acuto submediano, auricula antico magno, oblique radiatim lineatis ; 
auricula postica subnullo ; costulis radiantibus numerosis, costa una majora et minora al- 
ternatim instructis, semel varicibus duobus radiantibus magnis.  Lineis decussantibus densis 
regularibus ; valva afiva ignota. 
Shell with the left valve ovately orbicular, somewhat convex, the surface irregular, with 
unequal, undulating, radiating cost and concentric lines ; umbo acute, mesial straight, the 
anterior auricle large, with oblique radiating lines, the posterior auricle scarcely produced ; 
the surface of the valve has very numerous, unequal, radiating, rounded costz, in two series, 
a larger anda smaller coste being arranged alternately ; there are also two elevated, 
uregular, large, radiating varices upon the middle of the valve, as in Hinnites abjectus. 
The coste are about equal in width to the intercostal spaces; the entire surface of the 
shell has densely arranged, very regular, concentric lines, which are scarcely visible without 
the aid of a magnifier. ‘lhe other valve is unknown. 
Nearly allied, both in figure and aspect, to Hinnites abjectus, from which it is dis- 
tinguished by the regularity and smoothness of the costa and by the regular, concentric 
lines crossing both the cost and the intercostal spaces ; the latter are equal in width to the 
