CLASS PELECYPODA 
29 
perceptibly indent; surface sculptured only by feebly incremental lines; 
epidermis polished, with one or two darker concentric color zones and a 
microscopic, irregular, radially disposed wrinkling, most -conspicuous at 
the margins of the impressed ray; posterior cardinal margin nearly 
straight, anterior ditto evenly rounded; interior porcellaneous white, the 
pallial sinus not reaching the middle vertical line of the shell, broad and 
rather rounded, ligamental fosset large, -cup-like; anterior teeth V-shaped, 
about 22 in number, strong and prominent; posterior teeth similar, and 
forming an equally long line but only 18 in number, the posterior cardinal 
margin showing a long narrow impressed area very feebly marked. 
Length, 32; height, 17; diameter, 13 mm. (Dali.) 
Type in U. S. N. M., No. 106972. Type locality, U. S. Fish Com. 
Station 3202, in 382 fathoms green mud, Monterey Bay, California. 
Range. Chirkoff Island, Alaska, to San Diego, California. 
Yoldia martyria Dali, 1897. 
Plate 39, fig. 11. 
Nat. Hist. Soc. Brit. Col., Bull. No. 2:9; pi. 2, fig. 15. 
Shell olive greenish, polished, smooth, nearly equilateral; surface 
sculptured only by obsolete incremental lines; two or three extend obliquely 
backward from the beaks, due to some variation of color in the periostra- 
cum, but these do not interrupt the smoothness of the surface; beaks full, 
but not prominent; base arcuate, posterior end roundly pointed, com¬ 
pressed, slightly recurved; there is a long narrow, slightly impressed 
lunule and escutcheon, both of which are delicately striate longitudinally, 
and the dorsal margins included within them are not quite closed; the 
rostrum gapes slightly, but there is no obvious pedal gape; within the shell 
is white, with a deep rounded pallial sinus; chondrophore rounded, one- 
half of it projecting below the hinge plate; there are 21 anterior and 17 
posterior teeth, narrow, high, and rather strong. Length, 26; height, 5; 
diameter, 11 mm. (Dali.) 
Type in U. S. N. M. Type locality, off San Pedro Martir Island, 
Gulf of California. 
Range. Kana-an Bay, Alaska, to the Gulf of California. 
Yoldia vancouverensis E. A. Smith, 1880. 
Ann . Mag. Nat. Hist., (5), 6:289. 
Shell almost equilateral, transversely elongate-oval, acuminated pos¬ 
teriorly, slightly gaping at both ends, clothed with a greenish olivaceous 
epidermis, which is darker toward the ventral margin and varied at 
intervals with dark zones. Surface not very glossy, marked with con¬ 
centric lines of growth and close microscopic striations and granulation. 
Anterior side a trifle the longer, regularly rounded at the margin, posterior 
