CLASS PELECYPODA 
105 
umbonibus valde prominentibus, acutioribus; marginibus dorsalibus rectus, 
ad angulum 100° ; lunula minus impressa, longiore; area ligamentali minus 
angulata; dente laterali antico valva dextra extante. Long., .56; lat., .33; 
div., .21. (Carpenter.) 
Like compressa, but closer; dorsal margins straight, at right angles. 
(Carpenter.) 
Type in U. S. N. M.? Type locality, Puget Sound. 
Range. Forrester Island, Alaska, to Puget Sound. 
Astarte willetti Dali, 1917. 
Nautilus, 31:1:10. 
Shell small, of a yellowish-brown externally, milk-white internally; the 
external sculpture of small concentric waves is more regular and constant 
than in compacta; the form is more oval and the beaks more anterior than 
in that species, and willetti appears to attain a larger size. In compacta 
the lunule is relatively narrower and longer than in the new species. In 
the interior the hinge of the latter is better developed than in compacta, 
all three teeth being usually represented, while in compacta the posterior 
and particularly the anterior cardinal is frequently obsolete or absent. 
The shell substance of A. compacta is more translucent and bluish, and 
the crenulations of the valve margin when present are distinctly smaller 
and less conspicuous than in willetti. Length, 16; height, 14; diameter, 
9 mm. (Dali.) 
Type in U. S. N. M., No. 216364. Type locality, Forrester Island, 
Alaska. 
Range. Known only from the type locality. 
SECTION TRIDONTA Schumacher 
Astarte rollandi Bernardi, 1858. 
Plate 53, fig. 2. 
Jour, de Conch., 7 :386; pi. 13, fig. 4. 
Suborbicular, nearly smooth, large and heavy, with dark chestnut- 
brown periostracum, which in the adults is dehiscent on drying. This 
species takes the place in the western fauna occupied by A. castanea on 
the eastern coast. (Dali.) 
Type locality and disposition of the type not known to the present 
writer. 
Range. Pribilof and Aleutian Islands to Prince William Sound, 
Alaska. Also Kamchatka. 
