54 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
of which are divided toward the margin. Anterior ear (the larger) with 
7 ribs, the posterior ear with 5 ribs. This species resembles P. jordani 
Arn., but the valves do not tend to contract suddenly at the basal margin 
as in P. jordani , and the right ear is larger. The ribs on the valve of 
jordani are all divided from near the umbones. Length, 38; height, 40; 
diameter, 13; hinge line, 18 mm. (I. Oldroyd.) 
Type in Oldroyd Collection, Stanford University, No. 89. Type 
locality, off San Juan Island, Washington, in 25 fathoms. 
Range. Puget Sound. 
Pecten hindsii navarchus Dali, 1898. 
Plate 4, figs. 2, 3. 
Hinds, Voy. Sulphur, Moll., pi. 17, fig. 5 (as Pecten rubidus, Hinds, 1844, not Pecten 
rubidus Martyn, 1784), Dali, Trans. Wag. Inst., 3: pi. 4, 4,708. 
Shell smaller than P. islandicus ; ribs small, obscurely fasciculated, 
dichotomous, and imbricated on both valves. (Dali.) Alt., 55.5 ; long., 54; 
hinge line, 21; diameter, 17 mm. (Arnold.) 
Type in Museum Cuming. Type locality, Alaska. 
Range. Bering Sea to San Diego, California. In the Pleistocene of 
San Pedro and San Diego, at Pacific Beach, boulder clay of Comox, 
Vancouver Island, British Columbia. 
Pecten islandicus Muller, 1776. 
Plate 8, figs. 1, 2. 
Prodr. Zool. Danica, p. 248. Arnold, Tert. Pectens Cal., pi. 45, fig. 1. 
Shell suborbicular, somewhat higher than long, subequivalve, both 
valves only slightly convex, equilateral, except for ears; of medium thick¬ 
ness; sides only slightly concave above; base evenly rounded; color of 
living shell pinkish to salmon, the left valve being the more highly colored. 
Right valve with numerous narrow, square, flat-topped, imbricated ridges, 
which multiply slowly, both by division and intercalation, as the shell 
grows; interspaces narrow, channeled, and minutely reticulated; hinge line 
equal to more than one-half length of disk; anterior ear much produced, 
sculptured by numerous sharp imbricating lines and 5 or 6 major radiating 
ridges and some intercalate; byssal notch quite prominent; posterior ear 
a little over one-half as long as the anterior, and sculptured in the same 
way. Left valve similar to the right, except possibly that the imbrication 
is a little more pronounced. Length, 77; height, 83; diameter, 27; hinge 
line, 44 mm. (Arnold.) 
Type locality, northern seas. Location of type unknown to the 
present writer. 
Range. Arctic Ocean, Kamchatka and Puget Sound. Also Atlantic. 
