444 A. M Verrill — Mollusca of the JVeto England Coast. 



Crenella fragilis Verrill, sp. nov. 



Shell large for the genus, very thin and fragile, translucent, irides- 

 cent within, in form oblong-ovate, very ohliijue, the anterior end 

 short, a little expanded and broadly rounded, while the shell is very 

 much swollen and prolonged ventrally. The posterior side falls oflF 

 rapidly from the beak and is only a little convex, so that the margin 

 of the valve has a nearly elliptical outline, with the longer axis 

 extending from the beak to the ventral margin. The umbos are 

 prominent and the beaks are strongly incurved and turned forward, 

 and separated from the margin of the shell by a deep, narrow 

 ligamental groove. The hinge-margin is thin and nearly plain, with- 

 out any denticles. The ligament is long and extends from the front 

 of the beak back more than a third of the length of the posterior 

 margin. The sculpture consists of very regular, fine, radiating, 

 raised lines, scarcely visible without a lens, separated by furrows a 

 little wider; these are more or less interrupted by numerous fine but 

 irregular raised lines of growth. The epidermis is very thin, smooth, 

 pale olive. 



Height of the smaller example, from beak to ventral margin, 14"""; 

 length from anterior to posterior margins, 9""" ; thickness, 12'"'". A 

 broken specimen from the same locality is more than twice as large 

 as the one measured. 



Station 2,265, off Chesapeake Bay, N. lat. 37° 07' 40", W. long. 

 74° 35' 40", in 70 fathoms, green mud, gravel, and broken shells ; 

 bottom temperature 68° F. Two dead but fresh specimens (Nos. 

 40,676 and 41,543). 



This species is remarkable for its large size, compared with other 

 species; the extreme thinness and translucency of the sliell; and for 

 the fine and regular radiating lines that cover the entire surface. 



Pecten UndatUS Verrill and Smith, sp. nov. 



Plate XLTV, figure 21. 



Shell small, oblique, very thin, fragile and translucent. The valves 

 are similar in form and sculpture, but the left is a little more convex. 

 Both are regularly undvilated and everywhere covered by numerous, 

 i-ather fine and regular raised radiating lines. In the right valve the 

 anterior ear is considerably prolonged ; with a deep acute notch 

 below it ; in the other valve the ear is less elongated and the notch 

 is shallow and broadly concave ; the posterior ear in both valves is 



