212 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Pholadidea penita sagitta Stearns, 1916. 
Proc. U. S. N. M., 52:417. 
Shell closely similar to P. penita Conrad, but with shorter proportions, 
measured longitudinally, and with a corresponding widening of the dorsal 
appendages of the adult. (R. E. C. Stearns.) 
Type in U. S. N. M., No. 63312. Type locality, Monterey, California. 
Range. Puget Sound to Socorro Island. 
Pholadidea melanura Sowerby, 1834. 
Plate 22, figs. 9, 10. 
Proc. Zool. Soc., p. 70. Thcs. Conch. Pholas, pi. 107, figs. 78, 79. 
Shell closed, sub-ovate, divided in the middle by a serrated canal; 
anterior part with imbricated ribs; ventral margin smooth inflated, con¬ 
fluent with the back, dorsal margin strongly reflected and tumid, divided 
at the umbos by two sub-quadrate shields placed upon wide laminae; pos¬ 
terior part concentrically ridged, with a blackish epidermis, and at the 
end two horny, inflated sub-reniform swellings fixed to the shelly tube. 
Long., 1.4; lat., 0.75; alt., 0.08 poll. (Sowerby.) 
Type in British Museum. Type locality, Monte Cristo, Colombia. 
Range. Redondo, California, to Colombia. 
Pholadidea ovoidea Gould, 1851. 
Plate 21, figs. 5, 6, and plate 51, figs, la, lb, 2a, 2b. 
Proc. Boston Soc. Nat. Hist., 4:87. Boston Jour. Nat. Hist., 6; pi. 15, fig. 1. 
Shell ovoid, rather solid, chalky white, very widely gaping behind the 
beaks which are placed at the anterior fourth of the shell, slightly gaping 
also in front, the anterior ventral opening mostly closed by thick calcareous 
plates, one of which partially overlaps the other, somewhat marked by 
converging ridges; both extremities broadly rounded; disk of the valves 
divided by a broad sulcus barred by the lines of growth, and passing 
from the beaks to the middle of the ventral margin; posterior portion 
unsculptured; anterior portion ornamented with crowded, elevated, undu¬ 
lated concentric lamime, decussated by acute, radiating ribs arranged 
somewhat in pairs; in front of the beaks the dorsal margin is reflected, 
not appressed, and then doubled upon itself; cardinal valvular missing; 
interior yellowish white; cardinal apophysis long, slender, a little expanded 
and excavated toward extremity, directed obliquely backward. An exten¬ 
sive prolongation of the epidermis closes the posterior margins and forms 
a long tube for the protection of the siphons. Length, 3; height, 2; 
diameter, 1inches. (Gould.) 
Type locality, California. 
Range. Bering Sea to the Gulf of California. 
