HO. 1139. DEEP-WATER MOLLUSC A VERRILL AND BUSH. 809 



CARDIOMYA PERROST RATA Dall. 



(Pliit.es LXXIII, fig. 2; LXXIV, fig. 3.) 



Ncwra perrostrata VEURILL, Trans. Conn. Aead., \ , p. 501, 1XS2; VI, p. 277, 1884. 

 Cardiomya perrostrata DALL, Bull. Mus. Comp. Zool., XII, p. 1'ltH, pi. n, figs. 3a, 3ft, 

 188(5; Bull. U. S. Nat. Mus., No. 37, p. 66, pi. n, figs. 3a, 3I>, 1889. 



Only a few specimens were obtained from seven stations between N. 

 lat. 40 15' 30", W. long. 70 27', and X. lat. 39 4(3' 30", W. long. 70 

 54', in 58 to 325 fathoms, 3880-1884. 



South to Granada, in 339 to 416 fathoms. Ball. 



CARDIOMYA GEMMA, new species. 



(Plates LXXI, figs. 3, 4; LXXIV, fig. 11.) 



Neaira pan cistriata BUSH, Trans. Conn. Acad., VI, p. 473, 1885. 



Not Myonera paiicistriata DALL, Bull. Mus. Comp. Zool., XII, p. 302, 1886; Bull. 



U. S. Nat. Mus., No. 37, p. 68, 1889; Proc. U. S. Nat. Mus., XII, p. 233, pi. xin, fig. 



12, 1889. 

 Cardiomya sp. BUSH, Bull. Mus. Comp. Zool., XXIII, p. 227, 1893. 



Shell small, inequivalved, thin, fragile, translucent, bluish white, 

 somewhat ovate, with a well-defined rostrum. TJinbos smooth, a little 

 prominent; the beaks small, inconspicuous. The antero-dorsal margin 

 is convex and rises distinctly above the beaks so that the greatest 

 height of the shell is in front of them; thence it slopes rapidly to 

 the somewhat prominent anterior end; the ventral margin is broadly 

 rounded with a slight angle at the termination of each radial rib, 

 decidedly incurved at the base of the rostrum which is a little elon- 

 gated, nearly straight, somewhat tapered, and rather upturned distally ; 

 the postero dorsal margin is depressed and somewhat concave. Each 

 valve has three conspicuous, prominent, thin, elevated, distant, radial 

 ribs on the posterior half and a fourth less distinct one at about the 

 middle; this is rudimentary in the left valve; none of them reach the 

 umbos. The surface is also covered with very delicate lines of growth; 

 the rostrum does not have a diagonal ridge. The hinge-margin is thin 

 and delicate; the right valve has a small but prominent, moderately 

 long lateral tooth separated from the very minute cartilage-plate by a 

 distinct notch. The lateral tooth is supported by a small buttress. 



Length, 5 mm.; height, 3 mm. 



A few specimens off Cape Hatteras, North Carolina, in 1<> and 17 

 fathoms, 1884. 



