67 St. Maurice and Ci^aiborne Pelecypoda 67 



dorsal and anterior portions in front, lunule very narrow, excavated, with 

 the valve margins slightly pouting ; the escutcheon similar, wider, with an 

 excavated, obliquely grooved furrow outside of it, with rounded outer edges, 

 the whole forming a conspicuous, lanceolate area extending from the point 

 of the rostrum to the beaks; anterior end of shell rounded, base arcuate, 

 posterior end with a short, bluntly pointed rostrum, hinge solid, with about 

 sixteen anterior and fourteen posterior V-shaped teeth ; chondrophore small, 

 subumbonal ; the rostrum without an internal ridge, the pallial sinus small. 

 Length 5.2, alt. 3, diam. 2.5 mm. 



This interesting little species seems to be rather common in beds of 

 the Wautubbee horizon. It differs from L. robusta Aldrich in details of 

 sculpture, especially on the escutcheon. 



There is a somewhat noticeable flattening of the shell on pass- 

 ing from the middle to the rostral area, not so marked as in 

 ^^■^r/^^/a nor so sharply defined as in parva, still noticeable (see 

 fig. 12, a). 



This species differs from quircollis in its more marked median 

 inflation, somewhat greater size, coarser concentric ornamentation 

 on the central portion of the shell but lack of .same near the pos- 

 terior and anterior extremit}'. It is distantly related to robusta 

 Aldrich. 



Leda kittensis, n. sp., PI. 25. Fig. 6. 



Specific differentiation . — Size and appearance as illustrated ; 

 surface marked by about 30 concentric raised lines about one-half 

 as wide as the interspaces ; lines stronger mediallj^ and posterior- 

 ly than anteriorl)^ ; umbonal angle sharpl}^ defined by a 90 degree 

 angle ; concentric lines changing direction slightly, bending up- 

 ward, just before reaching the sharp ridge ; post- umbonal slope 

 marked very obliquely hy the continuation of the raised lines 

 above described, lines of about one-third the strength of those on 

 the main bod}- of the shell ; escutcheon very small, .scarcely per- 

 ceptible ; lower portion or the umbonal slope seemingly gouged 

 out concavel_v, above with a convex swell over both of which the 

 oblique lines evenly swing (convex swell, marking the termina- 

 tion of the posterior series of teeth); within, .showing two series 

 of teeth, the anterior but .slightly longer than the po.sterior, both 

 becoming weak and finall}^ vanishing exactly at the apex ; 

 .siphonal ridge emanating near the beak within and increasing in 



