808 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX. 



although the elevation and distance between them gradually increase 

 posteriorly, while in the former they are broadly rounded and separated 

 for the most part by narrow interstices. The hinge also differs consid- 

 erably; the cartilage-plate is less prominent and broader than that of 

 multicostata, and the tooth in the right valve is longer and not so 

 prominent and scarcely forms a notch at its junction with the cartilage- 

 plate; anteriorly the margin is very thin and simple with a very nar- 

 row, linear, ligamental groove -along its outer edge, while in the former 

 the groove is broader and its inner edge is raised almost in the form of 

 a lateral tooth. 



It also resembles C. costellata var. corpulenta Ball in the character 

 of the costa?, but the latter is much shorter and higher in form and has 

 a very short, ill-defined rostrum. 



Two young live specimens, two separate valves, and some fragments 

 were taken at three stations, between N, hit. 40 29', W. long. 66 14', 

 and K lat. 36 47', W. long. 73 9' 30", in 1,685 to 1,813 fathoms, 1885-86. 



CARDIOMYA MULTICOSTATA Verrill and Smith. 



(Plate LXXIII, fig. 3.) 



Neaera multicostata VERRILL, Trans. Conn. Acad., V, p. 559, pi. LVIII, fig. 40, 1882; 



VI, p. 277, 1884; Expl. Albatross, Keport U. S. Com. Fish and Fisheries for 



1883, pi. xxx, fig. 129, 1885. SMITH, E. A., Eeport Voy. Challenger, Zool. 



Laniellibranchiata, XIII, p. 36, 1885. 

 Not Cardiomya striatn BALL, Bull. Mus. Comp. Zool., XII, p. 298, pi. in, fig. 10, 



1886; Bull. U. S. Nat. Mus., No. 37, p. 66, pi. in, fig. 10, 1889; Proc. U. S. 



Nat. Mus., XII, p. 281, 1889. 



Cardiomya striata DALL, Bull. U. S. Nat. Mus., No. 37, pi. LXV, fig. 129, 1889. 

 Not Cardiomya costeUata (DESHAYES) var. curta DALL, Bull. Mus. Comp. Zool., 



XII, p. 297, 1886. 

 Necera multicostata var. curta VERRILL, Trans. Conn. Acad., V, p. 560, 1882. 



This comparatively rare species was found at but eight stations off 

 Marthas Vineyard, in 85 to 158 fathoms, 1880-1882. 



Although this species resembles Cardiomya striata (Jeffreys) in the 

 character of its sculpture, the marked difference in outline, especially 

 in its clearly defined rostrum, render it advisable to keep the two forms 

 separate until a careful comparison of the hinges can satisfactorily 

 decide the question of their identity. 



The two valves designated as variety curta have the radiating ribs 

 rounded and not angular, but fewer in number than the typical form, 

 and must be distinct from curia of Jeffreys, which Mr. Dall makes a 

 variety of costellata of Deshayes. 



