1918] Packard: Molluscan Fauna from San Francisco Bay 253 
PECTINACEA 
PECTINIDAE 
Hinnites Defrance 
Hinnites giganteus Gray 
Plate 17, figures la and 1b 
Hinnites giganteus Gray (1826), p. 103; Wood and Raymond (1891), p. 55. 
Pecten giganteus, Arnold (1906), p. 93, pl. 29, figs. 1, 2, 2a. 
Description—Arnold (1906) described this species as follows: 
‘‘Shell averaging about 75 millimeters in altitude, usually not quite so long 
as high, irregular, inequivalve, generally inequilateral on account of attachment 
to irregular surface; shell quite thick; margins smooth. Right valve more ven- 
tricose than left, ornamented by 9 to 18 narrow, irregular, prominently squamose 
ribs, between which in the flat interspaces are less prominent raised lines simi- 
larly sculptured; hinge line more than one-half length of disk; ears subequal, 
and more or less prominently sculptured by fine, squamose, radiating lines; 
byssal sinus sometimes visible. Left valve less ventricose than right, otherwise 
similar. Hinge rather narrow and heavy; fosset deeply excavated, oblique, 
narrow, and angular; hinge is dark purple in living shells.’’ 
Length, 7 to 75 mm. 
Occurrence —At stations D 5701 (1), D5702 (f.), D5712 (1), 
D 5735 (1), D5795 (2), D5800 (2), D5827 A (f.), D 5843 (2), 
D 5846 (7, 2), and questionably at D 5773, D 5801. 
This common West Coast species was reported by Wood and Ray- 
mond (1891) from San Francisco. It has been taken by the Survey 
at eight stations. It is restricted in its distribution to the open waters 
outside the Golden Gate and the middle portion of San Francisco Bay 
west of Alcatraz and north of Angel Island. The only living specimen 
was obtained at station D 5846 at a depth of 10 fathoms on a stony 
bottom. Shells were obtained in depths up to 19 fathoms from bottoms 
which were prevailingly stony. 
This correlation with a rocky bottom is due to the fact that this 
species becomes sessile at any early age, attaching itself to some foreign 
object. 
Range—Aleutian Islands to Magdalena Bay (Dall). 
Pecten Miiller 
Pecten hastatus Sowerby 
Pecten hastatus Sowerby (1842-87), p. 72, pl. 22, fig. 236; Wood and 
Raymond (1891), p. 55; Arnold (1906), p. 108, pl. 41, fig. 4, pl. 42, 
figs..1, la, 2, 2a. 
Description.—Arnold (1906) described this species as follows: 
“‘Shell averaging about 64 millimeters in altitude, slightly shorter than 
high, inequivalve, equilateral (except for ears), compressed and with serrate 
