CLASS PELECYPODA 
205 
Grippina californica Dali, 1912. 
Plate 15, figs. 1, 2, 3. 
Nautilus, 25:128. 
Shell minute, subtrigonal, whitish, solid for its size, finely concen¬ 
trically sculptured; beaks moderately elevated, smooth; inner margins of 
the valves smooth, the left valve with no hinge plate; a narrow lanceolate 
lunule and sub-equal, similar escutcheon present; each bounded by a 
marked ridge; outside of the escutcheon a second radiating ridge extends 
from the beak to the lower posterior margin of the valves but without 
producing a notable angulation of the margin. Interior of the valves dull 
white, the muscular impressions and pallial line distinct. Length, 2.5; 
height, 1.5; diameter, 0.7 mm. (Dali.) 
Type in U. S. N. M. Type locality, off San Diego, California. 
Range. Known only from the type locality. 
Family SAXICAVID2E. 
Genus PANOPiEA Menard, 1807. 
Shell equivalve, thick, oblong, gaping at each end; ligament external, 
on prominent ridges; one prominent tooth in each valve; pallial sinus deep. 
(Tryon. S. S. Conch.) 
Type. My a glycimeris Born. 
Distribution. Northern Seas, Mediterranean, Cape, Australia, New 
Zealand, Patagonia. 
Range in time. Inferior Oolite to the Pleistocene. 
Panopaea generosa Gould, 1850. 
Plate 2, figs. 1, 2. 
Proc. Boston Soc. Nat. Hist., 7:215. U . S’. Exploring Expedition Shells, figs. 507, 
507a. 
Shell large and ponderous, chalky white, of a somewhat quadrilateral 
form, the basal and hinge margins being nearly parallel; the posterior 
extremity broadly truncated, a very little obliquely, and the anterior 
extremity broadly rounded; anteriorly it gapes slightly, but posteriorly it 
gapes broadly, and the valves are here somewhat everted. The surface is 
coarsely undulated concentrically and covered by an obliquely, and some¬ 
what plumosely wrinkled, dirty yellow epidermis, the beaks are sharp 
and prominent, placed near the middle of the superior margin; the anterior 
umbonal slope is tumid, the posterior a little compressed. The hinge is 
rather slender, having a single elevated, erect, obliquely triangular tooth 
in each valve, with a pit behind that in the right valve, and a crest-like 
