MUSEUM OF COMPARATIVE ZOOLOGY. 301 



The valves are of a yellowish white, and one of them shows remnants of a 

 thin but rather tough greenish epidermis. 



SDBGEND8 TROPIDOMYA Dall and Smith. 



An anterior cardinal tooth in each valve; no lateral teeth; cartilage as in 

 Leiomya. Tropidophora Jeffreys, not Troschel nor Thompson. T;ype Necera 

 abbreviata Forbes. 



This is Section I of Smith. The type has the buttress fairly developed and 

 chiefly concentric sculpture. 



Subgenus hALONYMPHA Dall and Smith. 



An acute cardinal tooth in right valve; no other teeth in either valve; a 

 clavicular rib extending posteriorly in both valves, fossette small, central; 

 surface concentrically striate or smooth. Type Necera claviculata Dall. Sec- 

 tion K of Smith, who places here Necera injlata Jeff"reys and N. congenita 

 Smith. 



The latter appears different from anything I have seen. N. injlata has been 

 in some confusion. The specimens so marked in the Jeffreys collection in 

 Washington are of two kinds. One valve from " Porcupine expedition, 1870, 

 St. 16, 17 a," is a left valve of Halonympha claviculata Dall, fitting almost ex- 

 actly the right valve which served as my type. Those from " off Gomera, 

 Chall. exp.," and " Porcupine exp. 1869, St. 39," are Rhinoclama teres Jeffreys. 

 Whether there is an injlata not represented in the Washington series I do not 

 know; the figures in P. Z. S., 1881, pi. Ixxi. figs. 2, 8, in which the differences 

 seem a little strained, might both have been made from varieties of teres in the 

 collection. Smith notes something of the same kind in his description of 

 N. teres (N. gomerensis of references to Plate X.) in the report on the Challenger 

 bivalves, p. 50. 



Halonympha claviculata Dall. 



Neara claviculata Dall, Bull. M. C. Z., IX. p. 112, 1881. Smith, Chall. Rep. Lam., 



p. 52, not pi. ix. figs. 8 - 8 b. 

 Neoera injlata, Jeffreys, P. Z. S., 1881, p. 942. 1882; (partly). 



Plate II. Figs. 8, 2 a. 



Habitat. Station 44, 539 fms., one valve; Sigsbee, off Havana, 450 fms. 

 (]) fragment; Porcupine expedition, Atlantic Ocean, Station 16, or 17 a, 1870; 

 Challenger expedition. Station 33, in 435 fiithoms, coral mud, near Bermuda. 



In the Porcupine specimen it is clearly to be seen that the posterior muscle 

 was planted on the upper surface of the clavicle, which is therefore in this case 

 a myophore as well as a buttress. 



