NO. 1139. DEEP-WATER MOLLUSCAVEKEILL AND BUSH. 871 



YOLDIELLA SUBEQUILATERA (Jeffreys). 



Leda subet/uilatera JEFFREYS, Proo. /oul. So<-.. London, p. 579, pi. XLVI, fig. 



3, 187!. 

 Toldia 8nbe<jnila1era VERHILL, Trans. Conn. Acacl., VI, pp.229, 279, 1884 (in part); 



Expl. Mbalrwx, Report U. S. Com. Fish and Fisheries for 1883, p. 576, 1885 



(in part). 



Leda xnbeijiiilalera DALL, Bull. Mus. Com]*. /ool., XII, p. 252, 1886. 

 ) <>l,1i<t .sM&<yj/ateraDAix, Bull. U. S. Nat. Mus., No. :;7, ]>. 14, 1889. 



Several live specimens (No. 35204), from station 2037, N. lat. 38 53', 

 W. long. 69 23' 30", in 1,731 fathoms, 1883, have been referred to this 

 species. Although younger or smaller than Jeffreys's type, they agree 

 very closely with his figures and description. The shell is very small, 

 very thin and transparent, polished, lustrous, but scarcely iridescent 

 and marked only by microscopic lines of growth. It is rather com- 

 pressed, nearly elliptical in form, with the beaks prominent above the 

 dorsal margin and turned almost directly hi ward. Both ends are 

 obtusely rounded and nearly equal in length, so that it is impossible to 

 determine which is anterior and which is posterior by the external 

 characters; one end, supposed to be the anterior, is however slightly 

 broader than the other. There is no distinct ligament visible externally. 

 The hinge plate is nearly straight, the two series of teeth forming but a 

 slight angle. Interior not seen. 



Our specimens measure from 1.5 to 2.5 mm. in length. South to 

 Grenada, in <J2 fathoms. Ball. 



YOLDIELLA EXPANSA (Jeffreys). 

 (Plate XCVII, fig. 3.) 



Leda expansa JEFFREYS, Ann. Mag. Nat. Hist., p. 431, November, 1876; Proc. 



Zool. Soc., London, p. 580, pi. XLVI, fig. 4, June, 1879. 

 Not Yoldia i-xpansa VERRILL, Trans. Conn. Acad., VI, p. 279, 1884. 



Shell oblong-ovate, nearly equilateral, with the posterior end a 

 little more broadly rounded than the anterior; both regularly obtuse. 

 Both dorsal margins are slightly convex and slope but little. The 

 hinge-plate is moderately wide, gently arched, with sharp dorsal 

 margins, and is completely interrupted in the middle by a deep, 

 angular notch for the resilium which is rather large and dark and is 

 attached to the inner surface of the shell below the beak. In the right 

 valve, there are nmeposteriorteeth,includingoneor two very small prox- 

 imal ones, separated from the margin by a rather wide, smooth space; 

 those in the middle of the series are long, with tapered, acute tips which 

 are .bent upward and toward the beaks, and at base are V-shaped. 

 In the anterior series, which is a little the longer, there are ten teeth, 

 including two or three very small, proximal ones; the larger ones are 

 nearly erect with the tips less inclined than those in the posterior series; 

 they are separated from the margin by a plain space about as wide as 



