866 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX. 



YOLDIELLA JEFFREYSI (Hidalgo). 

 (Plates LXXXI, tig. 5; LXXXIII, fig. 3.) 



Lcda lata JEFFREYS, Aim. Mag. Nat. Hist., p. 431, November, 1876. 



Leda Jeffrey si JEFFREYS, Proc. Zool. Soc. London, p. 579, pi. XLVI, fig. 2, Jnne, 



1879. SMITH, E. A., Report Voy. Challenger, Zool. Lamellibranchiata, XIII, 



p. 234, 1885. 

 Not Yoldiajeffreysi VERRILL, Trans. Conn. Acad., VI, p. 229, 1884. 



Shell small, ovate- elliptical, somewhat thick for its size, rather swol- 

 len, covered with a glossy, iridescent, brownish yellow epidermis. The 

 posterior end is considerably the longer, somewhat narrowed, bluntly 

 rounded without any distinct rostrum, limbos rather prominent, some- 

 what swollen; beaks prominent, curved inward and backward. The 

 autero-dorsal margin is broadly convex, slopes a little and becomes 

 continuous with the rather regularly curved outline of the rounded 

 anterior end ; ventral margin is broadly and regularly curved without 

 any distinct flexure; the posterior end is obtusely rounded and not 

 defined by any radial lines or ridges, with the dorsal margin nearly 

 straight at first, usually slightly convex in the middle, and sloping 

 gradually. The surface beneath the epidermis is nearly smooth but 

 shows more or less distinct lines of growth, which sometimes have the 

 form of fine parallel striations. The hinge-plate is thickened and 

 rather strong; the two series of teeth are long and form a very obtuse 

 angle at the beak; the anterior is somewhat the shorter and more 

 oblique and a little curved. In our type specimen there are thirteen 

 anterior teeth of which three or four proximal ones are very small; and 

 fifteen posterior ones, including four or five small proximal ones; a 

 somewhat larger specimen has fifteen in the anterior series and eight- 

 een in the posterior. The two series are interrupted beneath the beak 

 by a small, well-defined, concave, triangular resilial pit supported on 

 the inner side by a distinct shelf-like projection. 



Length of the type- specimen, 5 mm.; height, 3.1 mm. Length of the 

 largest specimen, 5.6 mm.; height, 4.2 mm. 



Six separate valves, at three stations, between K. lat. 37 38' 40", 

 W. long. 73o 16' 30", and K. lat. 36 42', W. long. 74 30', in 727 to 1,423 

 fathoms, 1884-1886. 



As all of our specimens are much larger than the measurements 

 given by Jeffreys, they are referred to ~Y. Jeffrey si (Hidalgo) with some 

 doubt, although they appear to agree well with Jeffreys's figure of that 

 species in form and in the character of the hinge. 



YOLDIELLA LENTICULA (Mbller) variety AMELIA, new.- 



(Plates LXXX, fig. 9; LXXXI, fig. 4.) 



Nucula lenticula MOLLEK, Iml. Moll. Groenl., p. 17, 1842. 



Yoldia abyssicola TORELL, Spitzbergens Molluskfauna, p. 149, pi. i, ngs. 4, a-b, 



1859. 

 Portlandia lenticula G. O. SARS, Mollusca Reg. Arcticte Norvegise, p. 39, pi. 4, 



figs. 10, a-b, 1878. 

 Lena lenticula JEFFREYS, Proc. Zool. Soc., London, p. 577, June, 1879. 



