mo '] PROCEEDINGS OF THE NATIONAL MUSEUM. 269 



adductor, small, elongate-triangular, deep; margin smooth simple. 

 Longitude of shell 28 ; altitude 22 ; diameter 15 mm . 



Hab.— U. S. Fish Commission Station 2754, east of Tobago, in 880 

 fathoms, globigerina ooze; bottom temperature 37°.0 F. 



A number of loose valves of this interesting species were obtained as 

 above stated, but no specimens containing the soft parts. 



On a cursory examination this species was referred to the Vesicomya 

 section of the genus, but from a more thorough study it became evident 

 that it was more nearly allied to the typical Callocardia. The liga- 

 ment is delicate and though somewhat inset is wholly external. The 

 anterior dental lamina in the right valve has an elevated equilateral 

 triangular point; the upper lamina is also triangular, but has a short 

 anterior side and a long gradual posterior slope, the edge of which is 

 slightly undulated and grooved above, so that, while really continuous 

 with the posterior lamina which is slightly thicker, a vertical view as 

 in Fig. 2 gives the impression of two teeth. The anterior lamina is 

 the largest. Close to the outer margin of the ligameutary furrow is a 

 well marked ridge which forms the boundary of the escutcheon, but is 

 hardly visible in a profile view of the shell. 



Subgenus CALLOGONIA Dall. 

 Pallial line with a deep narrow sinus. 



Callogcmia Leeana Dall. 



Plate x, Figs. 6, 7, 8, 9. 



Callocardia (Callogonia) Leeana Dall, Bull. Mus. Couip. Zool., xvm, p. 440, June, 1889. 



Shell narrow, elongated, slightly compressed, white, with a pale yel- 

 lowish epidermis and a sculpture of faintly elevated fine concentric 

 lines coincident with the lines of growth; umbones not prominent; 

 anterior end rounded ; posterior end moderately, obliquely subtruncate 

 rounded off above, slightly pointed below ; there is no line circum- 

 scribing a lunular space, and the ridge, if any, bordering the ligament 

 is so fused with the margin of the ligameutary groove that the shell 

 may be said to have no escutcheon ; there are a few irregular extremely 

 faint radiating lines, and a rounded ridge hardly defined extends from 

 the beaks to the lower posterior angle. Internally the shell is smooth, 

 white; the adductor scars larger proportionally and rounder than in 

 C. Smithii, the pedal scar deep but relatively smaller; the pallial line is 

 broad, with a deep angular sinus ; the margin simple, smooth; in the 

 right valve the anterior lamina is longest and is concave upward with 

 a rounded profile; the middle lamina is strongly bent with the angle 

 upward and is higher than the others; to it is attached the short thin 

 posterior lamina which is the lowest of the three with a sort of socket 

 above for the corresponding lamina of the other valve; the posterior 



