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 die 
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 ii mm. 
Creaipectevi senilis. -‘^P- ”• 
(Plate III, Fig. i. ) 
The limited number of aviculopectenidae found in the Waverly 
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. Felt 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 obsole.'^cent, fbtuse, entire pos- 
terior outline a gently convex curve slightly straightened near the 
hinge, ^surface marked by large, very irregular, convex, rounded 
plicae which increase without regularity by subdivision into a small and 
large plica 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, d'he plicae are sep- 
arated only by a deep, narrow, angular groove. Length 29 mm, 
width about the same; anterior ear 8 mm. 
The single specimen seems to have been derived from the free- 
stone. dTe peculiar markings serve to distinguish this from the other 
known forms. It bears a close resemblance in outline to Streblopteria 
media. 
Avicnlopecten {Lyrio})ecten?) cancellatus, sp. n. 
(Plate XII, Fig. 7.) 
Shell small, suborbicular ; length and height equal; lower and - 
