A. E. Verrill—MoUusca of the Neio England Coafit. 221 



Porcupine and Valorous Expeditions, and in the Bay of Biscay by 

 the Travailleur Expeditions. It has occurred at depths ranging from 

 652 to 1450 fathoms. 



LAMELLIBRANCHIATA. 

 Thracia nitida Verriil, sp. nov. 



Plate XXXII, figure 22. 



Shell thin, tumid, broad-ovate, gaping considerably posteriorly and 

 slightly anteriorly. Umbos prominent, situated in advance of the 

 middle, with the beaks strongly incurved and turned forward, leav- 

 ing a broad, depressed, cordate lunular area, which is not defined by 

 any definite boundary. The posterior dorsal margin descends 

 slightly ; the posterior margin is slightly prolonged and bluntly 

 rounded ; the ventral margin is broadly curved, becoming nearly 

 straight in the middle ; the anterior margin is obliquely rounded. 

 The surface is nearly smooth, shining, and iridescent, marked with 

 inconspicuous lines of growth, and covered with very minute, regu- 

 larly scattered granule-like elevations, each of which bears a minute 

 hair-like process, when not rubbed ; towards the posterior end these 

 are more numerous and conspicuous, and are arranged in regular deli- 

 cate radiating lines, but over the greater part of the shell they are 

 scarcely visible to the naked eye. Epidermis very thin, greenish 

 yellow. Hinge-margin slendei', somewhat thickened alpng the liga- 

 mental groove, and with a slight notch anteriorly for the reception 

 of the minute cartilage. No ossicle was detected in the alcoholic 

 specimen. Pallial and muscular impressions faint. 



Length, 21™"" ; height, 18""" ; thickness, 14"". 



The animal has a circle of sixteen large, tapered, acute tentacles 

 around the common base of the siphons, which are brown in alcohol. 

 The eiferent tube is somewhat prolonged in the contracted specimen, 

 but the other is entirely withdrawn. 



Station 2097, off Chesapeake Bay, in 1917 fathoms (No. 35,267). 



Poromya Sublevis Verriil, sp. nov. 



Plate XXXII, figure 21. 



Shell rather large for the genus, short, high, tumid, with prominent 

 umbos and large beaks, which are curved inward and forward. The 

 length of the shell is considerably less than the height from the beak to 

 the ventral margin. Anteriorly the lunular region is large and some- 



