CLASS PELECYPODA 
175 
Macoma leptonoidea Dali, 1895. 
Nautilus , 9:33. Proc. U. S. N. M., 23:308, 323; pi. 4, figs. 4, 9. 
Shell very thin, short, high, polished, smooth or with fine silky con¬ 
centric striulae under a thin iridescent epidermis; hinge very feeble, teeth 
as in M. limula; pallial sinus irregular, reaching about two-thirds the 
whole length, backward from the front edge of the valves; outline of 
valves leptonoid, the anterior slope longer and more rounded, the posterior 
shorter and more direct but not rostrate, though there are two obscure 
ridges radiant backward from the beaks but not modifying the posterior 
margin; the shell is somewhat compressed but not flattened. Length, 13; 
height, 16; diameter, 6 mm. (Dali.) 
Type in U. S. N. M., No. 125532. Type locality, Matagorda Bay, 
Texas. 
Range. Santa Barbara Channel. Also Texas coast. 
Macoma quadrana Dali, 1916. 
Plate 3, fig. 6. 
Proc. U. S. N. M., 52:414. 
Shell small, white, polished, intermediate between M. carlottensis 
Whiteaves and M. inflatula Dali, but smaller than either; periostracum 
pale straw color, slightly iridescent, microscopically concentrically striated; 
anterior end larger, posterior end short, obliquely subtruncate, the rostrum 
slightly bent to the right; the right valve a little flatter than the left; two 
faint low riblets extending from the beaks to the posterior basal angle; 
hinge very weak, pallial sinus deep and high. Length, 19; height, 13.5; 
diameter, 7 mm. (Dali.) 
Type in U. S. N. M., No. 225421. Type locality, Point Conception, 
Station 2892, in 284 fathoms. 
Range. Boca de Quadra, Alaska, to Coronado Islands, Lower Cali¬ 
fornia. 
Macoma carlottensis Whiteaves, 1880. 
Rep. Progress Geol. Surv. Canada, 1879-80, p. 196 B, fig. 1. 
Shell small, moderately inflated, thickness rather more than one-lialf 
the height, inequilateral; valves slightly flexed to the right posteriorly; 
test thin and fragile. Anterior side produced, evenly rounded at its ex¬ 
tremity, and nearly twice as long as the posterior side; posterior side short, 
much narrower than the anterior, subcuneiform, sloping convexly and 
abruptly from above downward, and at last forming a subangular junc¬ 
tion with the ventral margin below. Ventral margin gibbous in advance, 
ascending and much straiter behind. Beaks small, moderately prominent, 
incurved, and placed considerably behind the middle. Ligament short, 
external. Surface glossy, marked by very fine, close-set, concentric stria- 
