804 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL xx. 



defining the base of the rostrum. The surface is nearly smooth and 

 somewhat glossy, covered with fine lines of growth which become more 

 prominent and irregular on the rostrum, which has no distinct diagonal 

 line. The hinge-margin is somewhat thickened; the right valve has a 

 rather short, prominent, obtuse, triangular lateral tooth only slightly 

 separated from the cartilage-plate by a concave margin ; the cartilage- 

 plate is small, very oblique, with the inner edge curved and not at all 

 angulated. Muscular scars and pallial line indistinct; no buttress. 



Length, 13 mm.; height, 9 mm.; breadth, G mm.; from beak to end 

 of rostrum, 8 mm.; from beak to anterior end, 7 mm. 



Found at about thirty stations between 1ST. lat. 40 2' 49", W. long. 

 68 49', and N. lat. 37 23', W. long. 73 53', in 302 to 984 fathoms. 



This species resembles C. obcsa (Loven) in form; it is, however, a 

 larger species with a firmer and more swollen shell; the ventral margin 

 is more prominent, so that it has a relatively higher form and is broader 

 at the base of the rostrum. The hinge shows more decided differences, 

 for in C. obesa the lateral tooth is smaller, shorter, and closely approxi- 

 mated to the cartilage-plate which is distinctly angulated, the inner 

 end being acute and separated from the tooth by a small angular 

 notch. 



CUSPIDARIA OBESA (Loven) Dall. 



( Plate LXXV, fig. 7.) 



Necara obesa LOVKN, Ind. Moll. Scand. Occid., p. 48, 1846. VERIULL, Trans. 



Conn. Acad., V, p. 563, pi. XLIY, fig. lOc, 1882; VI, p. 277, 1884 (in part) ; Expl. 



Albatross, Report U. S. Com. Fish and Fisheries for 1883, p. 574, 1885 (in 



part). SMITH, E. A., Report Voy. Challenger, Zool. Lamcllibraucliiata, XIII, 



p. 43, 1885. 

 Cuspidaria obesa DALL, Bull. Mus. Comp. Zool., XII, p. 295 (not pi. in, fig. 1), 



1886; Bull. U. S. Nat. Mus., No. 37, p. 66 (not pi. in, fig. 1), 1889. 

 Not Necvra pellucida STIMPSON. 



This species has been found at about twenty-four stations between H". 

 lat. 43 23', W. long. 68 30', and N. lat. 35 12' 10", W. long. 7457 / 15 // , 

 in 96 to 811 fathoms, 1873-1887. 



It is recorded by Mr. Dall from off Barbados in 100 fathoms and off 

 the coast of California in 16 fathoms. 



After a careful study and comparison of the numerous species 

 belonging to the family Cuspidaridte we have been able to satisfac- 

 torily prove that the form described by Stimpson as Necera pellucida is 

 quite distinct from that described by Loven as N. obesa, with which it 

 has been so long confounded. 



