54 BULLETIN OF THE LABORATORIES 



sal sinus below the ear ; the posterior ear is less sharply defined by the 

 umbonal ridge, but is lower than the plane of the body and its margin 

 passes into that of the valve by a moderate curve. Although both 

 ears are provided with well defined radial and concentric striae none 

 appear clearly in any of the specimens on the body of the valve. 

 The hinge of the left valve is crenulated as in A. winchelli, which ihe 

 right valve resembles. The very convex left valve and surface char- 

 acters serve to distinguish it from other species. 



Height 14 mm ; length 14 mm; length of hinge 11 mm. 



Crempecten senilis. H^- "• 

 (Plate III, Fig. I.) 



The limited number of aviculopectenidas found in the VVaverly 

 induces me to propose a name for this species known only from the 

 left valve. 



Shell of medium size, nearly circular or elliptical in outline; 

 rather flat. Leit valve slightly convex, with a moderately acute de- 

 pressed beak ; anterior wing large, separated from the body by a mod- 

 erate umbonal ridge, its outline passing into that of the body by a 

 flowing sigmoid curve ; posterior ear obsolescent, c btuse, entire pos- 

 terior outline a gently convex curve slightly straightened near the 

 hinge, c^urface marked by large, very irregular, convex, rounded 

 plicae which increase without regularity by subdivision into a small and 

 large i)lica or the plicae are proliferous without sensible diminution of 

 size of the primary one. The anterior ear is similarly plicate and, 

 like the body, is crossed by fine concentric striae. The plicae are sep- 

 arated only by a deep, narrow, angular groove. Length 29 mm, 

 width about the same ; anterior ear 8 mm. 



The single sjjecimen seems to have been derived from the free- 

 stone. The peculiar markings serve to distinguish this from the other 

 known forms. It bears a close resemblance in outline to Streblopteria 

 media. 



Avicitlopecten {Lijriopecteri?) cancellatits, sp. n. 



(Plate XII, Fig 7.) 



Shell small, suborbicular ; length and height equal; lower and 



