CLASS PELECYPODA 
53 
Type in U. S. N. M., No. 150207. Type locality, Station 3313, 
Iliuliuk Harbor, Unalaska, in 68 fathoms. 
Range. Aleutian Islands. 
Pecten hastatus Sowerby, 1843. 
Plate 29, figs. 1, 3. 
Thes. Conch. Pecten, p. 72; pi. 20, fig. 236. 
Shell oval, inclining to triangular, rather elongated, rough, with very 
unequal ears, the posterior ones being very small; the upper valve has 
eight unequal, elevated, angular ribs, with numerous erect, slightly curved, 
sharp spines, and several smaller spinose ribs in the interstices. 1 he lower 
valve has 22 more nearly equal ribs, with more numerous and smaller 
spines on the angle. Long. 54; alt., 61; hinge, 28 mm. (Sowerby.) 
Type in Cuming Coll. Type locality not given. 
Range. Monterey to San Pedro, California. 
Pecten hindsii Carpenter, 1864. 
Plate 7, figs. 3, 4. 
Suppl. Rep. Brit. Assoc., p. 645. Arnold, Tert. Pectens Cal., pi. 43, figs. 1, 2. 
Shell smaller than P. hericius , margins smooth. Right valve with 
about 26 close-set, sometimes wide, flattish, usually dichotomus, smooth 
ribs, which show fine lines of growth on their surface; interspaces narrow, 
channeled, and sculptured by minute reticulations; hinge line one-half as 
long as disk; anterior ear produced, sculptured by about six radials and 
prominently imbricating concentric lines; byssal notch prominent; pos¬ 
terior ear small and with radial and imbricating concentric sculpture. Left 
valve with small, obscurely fasciculated, imbricated ribs, each fascicle 
having one major and several much smaller and more prominently imbri¬ 
cated riblets; interspaces very narrow and sculptured as in the right valve; 
ears similar to those of right valve except lacking notch in anterior one. 
Color pink to white, the left valve being darker. Length, 57; height, 58; 
diameter, 18 mm. (Arnold.) 
Type in British Museum. Type locality unknown. 
Range. Bering Sea to San Diego, California. 
Pecten hindsii kincaidi I. Oldroyd, 1919. 
Plate 12, figs. 1, 2. 
The Nautilus, 33:135; pi. 4, figs. 3, 4. 
Shell suborbicular, the height and length being nearly equal; equi- 
valve, both valves slightly convex; ears as in P . islandicus; base evenly 
rounded; color yellowish white with reddish brown markings. Left valve 
with 28 narrow round-topped imbricated ribs, and very faint intercallaries, 
the interspaces wider. Right valve with 25 broader flat-topped ribs, some 
