BIVALVIA. 35 



squamafis, iiifcrvallis, trip/ohttioribus ; costis extremis minoribtis ; auricidis subaqualibus, 

 transverse lamelhsis. Valva dextra convexiori qiiinquesulcata, concentrice tomiter lamellosa ; 

 sulcis concavis, costis altera valva respondentibus ; costis latioribus convewis, subdivisis. 

 (Buvignicr.) 



Shell suborbicular, inequivalve, depressed. The left valve nearly flat, with fine radiating 

 ribs, separated by very wide intervals ; the costal have large, scpiamous plications, rather 

 irregular, and nearly disappearing as they ap])roach the apex, the costse near to the margins 

 being the smaller ; the intervals between the costse 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 costse of the other 

 valve; the whole surface of the valve is covered with delicate, regular, concentric, closely 

 arranged lamellge. The interior of the valves present an appearance corresponding v\ ith 

 the ornamentation of the exterior. 



Height jather 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. Buvignier quotes the species from the lower ferruginous beds of the Oxford 

 Clay, Ardeinies and Meuse. 



HiNNiTES GRADUs, Bean^ sp. Tab. XXXIII, figs. 10, 10 a. 



Pecten grab OS, Bean. Mag. Nat. Hist., 1839. 



Testa valva sinistra, ovate orbiculari convexo-plana, radiatim vndulato cost at a et con- 

 centrice lineata ; wnboni acufo 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 mapiis. Lineis decussantibus densis 

 regularibus ; valva ajjixa ignota. 



Shell with the left valve ovately orbicular, somewhat convex, the surface irregular, with 

 unequal, undulating, radiating costse 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 costse, in two serfes, 

 a larger and a smaller costse being arranged alternately ; there are also two elevated, 

 irregular, large, radiating varices upon the middle of the valve, as in Hinnites abjectus. 

 The costse are about equal in width to the intercostal spaces ; the entire surface of the 

 shell has densely arranged, very regular, concentric hues, which are scarcely visible without 

 the aid of a magnifier. The other valve is unknown. 



Nearly allied, both in figure and aspect, to Rhinites abjectus, from which it is dis- 

 tinguished by the regularity and smoothness of the costse and by the regular, concentric 

 lines crossing both the costse and the intercostal spaces \ the latter are equal in width to the 



