CLASS PELECYPODA 
173 
Macoma oneilli Dali, 1919. 
Plate 40, fig. 7. 
Sci. Res. Canadian Arctic Exp., 8: pt'. A, 20A; pi. 2, fig. 1. 
Shell small, thin, oval, compressed, inequilateral, slightly inequivalve, 
the anterior part more than twice as long as the part behind the umbos; 
white, covered with a dehiscent yellowish olive periostracum; beaks hardly 
perceptible, ligament prominent, posterior end with an extremely narrow 
compressed dorsal margin corresponding to the fold of most species; 
anterior and posterior ends subequally rounded; dorsal and basal margins 
nearly equally arcuate; interior chalky white, the hinge with two small 
but well-marked teeth in each valve, the anterior left cardinal bifid; 
pallial sinus rounded behind, coalescent below, a little smaller in the right 
valve than in the other; muscular impressions subequal and of moderate 
size. Length of shell, 21; length in front of the vertical from the beaks, 
15; height, 15; diameter, 6 mm. (Dali.) 
Type in Ottawa, No. 4240. Type locality, Dolphin and Union Strait, 
Arctic. 
Range. Known only from type locality. 
Macoma moesta Deshayes, 1854. 
Proc. Zool. Soc., p. 361. Proc. U. S. N. M., 23; pi. 4, fig. 8. 
T. testa regulariter ovata, transversa, crassiuscula, tumidula, tenui, 
valde insequilaterali, sub epidermide tenui, pallide viridi-flavicante alba, 
subcretaces, transversim obsolete striata, striis, latis, subplanis, irregu- 
laribus; latere antico longiore, obtuso, margine inferiore superioreque 
convexiusculis, parallelis; latere postico obtuso, paulo angustiore, flexura 
parum profunda; ligamento brevi, partim infosso; cardine angustissimo, 
bidentato, dentibus minimis, laterali antico nullo, postico obsoleto; sinu 
pallii brevi, late ovato. (Deshayes.) 
Shell ovate, inflated, smooth, thin very inequilateral, equivalve, cov¬ 
ered with a greenish epidermis; posterior side short, slightly angular, 
finely concentrically wrinkled at the angle, narrow behind the angle; dorsal 
margin sloped, and subtruncated; anterior side rather obliquely produced. 
Cardinal teeth small, lateral teeth none. (Conch. Iconica.) 
Type in Museum Cuming. Type locality, Northern Ocean. 
Range. Arctic Ocean, Bering Sea, Shumagin Islands. Also Atlantic. 
Macoma calcarea Gmelin, 1792. 
Plate 42, fig. 5. 
Syst. Nat., 7:3236. Conch. Cab., ed. 1, 6:140; pi. 13, fig. 136. 
Shell ovate, white, smooth, covered with a thick epidermis; posterior 
side rather short, slightly compressed, scarcely radiately angular, with 
