MUSEUM OF COMPARATIVE ZOOLOGY. 283 
Poromya (Cetoconcha) elongata, n. s. 
Shell whitish, not pearly, somewhat resembling the preceding, but much 
more elongated; surface more densely and minutely granulate, the granules 
being in even radiating series for the most part; the lines of growth are 
stronger and the surface not so smooth; the epidermis is similar, but appar- 
ently thinner ; the beaks are contiguous, and are less elevated, less spiral, and 
less prominent ; the hinge-line, though longer, is thinner; the cardinal tooth 
more acute and much smaller ; the shelf for the cartilage weaker, longer, and 
narrower; the ridge extending backward from the beaks is not so near the 
hinge-margin, and the area between is wider and obliquely cut off at its pos- 
terior end, forming a more decided angle than in C. albida ; the anterior end 
and base are elegantly rounded, but the posterior end is somewhat rostrated 
with an obscure impression extending from the beaks to the lower posterior 
rounded angle of the rostration ; the beaks are nearly equidistant from the 
ends, but probably a little behind the median line; the hinge-margin in the 
right valve is a little expanded before the beak. Lon. 22.5 ; alt. 17 ; diameter 
of right valve 6.25; of shell, probably, 12.5 mm. 
A single right valve was obtained by the “‘ Blake” at Barbados, in 100 fms.; 
and a living specimen by the U.S. Fish Commission at Station 2337, north- 
west of Cuba, in 199 fms. It has somewhat the shape of Poromya neeroides 
Seguenza, but the hinge differs. The soft parts are described in the sub-generic 
diagnosis with some additional notes under the next species. The lower palpi 
are absent, and the gill rows one on each side, adjacent, but not touching, at 
the point of origin without any appendix. 
Poromya (Cetoconcha) bulla Dall. 
Lyonsia bulla Dall, Bull. M. C. Z., VI. p. 61, 1878; IX. p. 107, 1881. 
(2?) Thracia nitida Verrill, Trans. Conn. Acad., VI. p. 221, pl. xxxii. fig. 22, 1884. 
Habitat. Station 31, Gulf of Mexico, in Lat. 24° 33’ N., Lon. 84° 23’ W., 
1920 fms., living, bottom temperature 39°.5 F.; U. S. Fish Commission (as 
Thracia nitida), off Chesapeake Bay, in 1917 fms. 
The agreement between Professor Verrill’s figure and description on the one 
hand, and the Blake specimens on the other, is so close, that I can hardly 
doubt they are the same species, though I have not examined specimens of his 
shell. The soft parts of this species are much the same as in C. elongata, ex- 
cept that the retractile siphon is proportionately longer, and the gill series 
consists of two short rows (5-7 lamelle) on each side radiating forward from 
a point immediately behind the foot. The lower palpi are present but not 
branchial; but on the body surface near them are two short rows (8-10 sec- 
tions or lamellze), one on each side, diverging backward, the anterior end of 
each being under or behind the lower palpus of that side. The trend of these 
