298 BULLETIN OF THE 



Cardiomya costellata, var. corpiilenta Dall. 



Plate HI. Fie. 9. 



The variety corpuUnta Dall is like a giant curta striated all over, and about 

 15.0 mm. long. A valve was dredged at Station 5, in 229 fnis., and a frag- 

 ment at Station 228, near St. Vincent, in 785 fms. It differs from C. striata 

 Jeffreys in the shorter and less differentiated rostrum and the alternate!}' larger 

 and smaller radii, which are also more distant and sharper, while the concen- 

 tric striae are much less evident. Still, in the type these characters intergrade, 

 as they might be seen to do here if we had specimens enough to compare. 



Cardiomya striata Jeffreys. 



Necera striata Jeffreys, Valorous Moll., Ann. Nat. Hist., Dec. 1876, p. 495 ; P. Z. S., 



Nov. 1881, p. 944, pi. Ixxi. fig. 11, 1882. 

 ? NeoEra aJternata D'Orb., var., Dall, Bull. M. C. Z., IX. p. 110, 1881. 

 Necera multicostata Verrill and Smith, Trans. Conn. Acad. Sci., V. 659, pi. Iviii. 



fig. 40 ; Proc. U. S. Nat. Mus., III. p. 398, 1880. 



Plate m. me. lo. 



Habitat.- Station 36, 84 fms.; Station 5, 152 fms.; U. S. Fish Commission, 

 off the Carolina coast, Station 2601; off Martha's Vineyard, Station 1038, etc.; 

 off Newport, Rhode Island, Station 874, and, others. 



This fine shell differs from some of the varieties of C. costellata only in size. 

 It bears the same relation to them that the var. corpulenta does to the var. 

 curta. But taken by itself it seems so distinct that I have concluded to leave 

 it separate for the present. It should be stated that Dr. Jeffreys' remark as 

 to the radiation not being coarser posteriorly, is correct only for the one or two 

 specimens first obtained, and even in them it is only partially exact. The vast 

 majority have the sculpture decidedly stronger toward the rostrum. I may 

 also add, that none of the specimens in the Jeffreys collection at Washington 

 have the rostrum quite as straight as in the figure in the P. Z. S. It is a little 

 upturned in all of them, though the particular specimen figured may not have 

 had that peculiarity. 



There is every probability of the correctness of Prof. Verrill's observation: 

 " Perhaps all these forms may eventually prove to be varieties of one species." 

 (Trans. Conn. Acad. Sci., V. p. 560, 1882 ) 



Subgenus LEIOMYA A. Adams. 



Leiomya A. Adams, Ann. Mag. Nat. Hist., 1864, p. 208. 



An anterior prominence or cardinal tooth in each valve, anterior and pos- 

 terior laterals in the right valve, left valve without laterals. Cartilage in a 



