78 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Modiolaria seminuda Dali, 1897. 
Plate 28, fig. 1. 
Bull. Nat. Hist. Soc. Brit. Col., 2:5; pi. 1, fig. 1. 
Shell short, thin, inflated, with a polished greenish epidermis; beaks 
turgid but not prominent; surface divided by the sculpture into three areas; 
the anterior small, with coarser, radiating riblets; the middle, smooth and 
larger; the posterior, covering about two-thirds of the shell, finely 
radiately striate; the only concentric sculpture is that of the delicate lines 
of growth. Interior of the valves with a pale whitish nacre, the sculpture 
showing through and denticulating the margin; thickening below the 
beaks inconspicuous, finely denticulate; ligament thin, short, not prominent. 
Extreme length of shell, 12; height, 9; diameter, 7.5 mm. (Dali.) 
Type in U. S. N. M.? Type locality, Markoffski Bay, Unalaska. 
Range. Bering Sea to Forrester Island, Alaska. 
Modiolaria vernicosa Middendorff, 1849. 
Plate 28, fig. 11. 
Mai. Rossica, 3:20; pi. 11, figs. 25-27. 
This species may be recognized by its smooth surface and reddish 
brown, brilliantly polished epidermis. 
Type. Neither the location of the type nor the type locality is known 
to the writer. 
Range. Bering Sea to Sitka, Alaska. 
Modiolaria phenax Dali, 1916. 
The Nautilus, 28:12:138. 
Shell small, very solid, inflated, brownish or bluish black, mytiliform; 
anterior end very short, but with the beaks extending slightly in front, 
attenuated, rounded, compressed below, with two or three radial, im¬ 
pressed sulci; posterior end widening, rounded, the dorsal margin with 
an obscure angle about midway, the base behind the sulci convexly 
arcuate; the beaks blunt, inflated, conspicuous; surface polished, with 
inconspicuous incremental irregularities; interior blackish purple, with a 
very strong nymph for the ligament, and three or four denticles where the 
external sulci meet the margin. Length, 7.7; height, 4.5; diameter, 4 mm. 
(Dali.) 
Type in U. S. N. M., No. 271733. Type locality, St. George Island, 
Pribiloff group, Bering Sea. 
Range. Known only from the type locality. 
