48 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Range in time. Lower Silurian, a few in the Tertiary, Eocene, 
Oligocene, Miocene. 
Pteria viridozona Dali, 1916. 
Proc. U. S. N. M., 52:403. 
Shell small, oval, translucent, sea-green, distributed in narrow darker 
and lighter zones, sculptured with narrow, very elongate, opaque, whitish 
scales, distributed in radiating lines with wider bare spaces between them; 
right valve smaller and flatter with a sinus for the byssus; left valve larger 
with the anterior ear compressed but not sinuate; the hinge line shorter 
than the shell with a shallow rounded sinus between the posterior ear and 
the body of the disk; interior with the pearly area small and no denticula- 
tions on the hinge line. Length, 25; height, 13; diameter, 5 mm. (Dali.) 
Type in U. S. N. M., No. 172600. Type locality, Long Beach, Cali¬ 
fornia. 
Range. Known only from the type locality. 
Pteria sterna Gould, 1851. 
Plate 40, fig. 3. 
Proc. Boston Soc. Nat. Hist., 4, p. 93, and 6, p. 404. Mex. and Cal. Shells- 
pi. 16, fig. 7. 
Shell rather solid, obliquely ovate, triangular, with a very long slen¬ 
der, acuminate cauda, and well marked auricles; color dark mahogany 
brown, with a few paler radiations; surface compactly striate, covered 
with a thin, dirty, cinerous epidermis, very delicately fringed with radi¬ 
ating series of minute processes, especially in the vicinity of the byssal 
notch and at margin. Beaks near the anterior fourth, prominent, oblique, 
the posterior umbonal slope tumid, and in the left valve limited by an 
obtuse groove, a submarginal angle along the cauda; auricles radiately 
striate. Auricle of right valve trapezoidal, widening toward the tip and 
obliquely truncate; byssal notch deep and acutangular; auricle of left 
valve subtriangular, as broad as long, the byssal fold prominent. Hinge 
with a well marked cardinal and lateral tooth in left valve. Nacre silvery 
and highly iridescent; margin like the tortoise shell. Length of hinge 
margin, two and a half inches; diameter of wing, one and one-fourth 
inches; breadth, five-eighths of an inch. 
Type in Boston Soc. Nat. Hist. Type locality, Mazatlan, Mexico. 
Range. San Diego, California, to Panama. 
Genus PEDALION Solander, 1770. 
Shell nearly equivalve, compressed, subquadrate; area wide, cartilage 
pits numerous, elongate, close-set; right valve with a byssal sinus; muscu¬ 
lar impression double. = Perna Brugiere, 1792. (Tryon. S. S. Conch.) 
