142 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Torellia ammonia Dali, 1919 
Proceedings of the United States National Museum, 56:355. 
Shell large, cartilaginous or leathery, depressed, brown, of somewhat 
more than two whorls; the nucleus, comprising a little more than one 
whorl, has spiral elevated lamellae with wider interspaces, much as in the 
larval envelopes of Lamellaria , but on a larger scale; the remainder of the 
shell has close-set axial fringed lamellae; the suture is deep, the aperture 
entire, wider than high; the umbilicus is pervious, moderately wide, as in 
Planorbis trivolvis , the animal is distinctly Velutinoid, and carries no oper¬ 
culum. Height, of dry shell, 12; greatest diameter, 24 mm. (Dali.) 
Type in United States National Museum, No. 111367. Type locality, 
southwest of Sannakh Island, Alaska, U.S. Fish Commission Station 3213, 
in 41 fathoms. 
Range. Known only from type locality. 
Family LEPETIDAE 
Genus LEPETA Gray, 1847 
Shell patelliform, the embryonic nucleus spiral, lost in the adult, apex 
in front of the middle; no internal septum. 
Type. Lepeta caeca Muller. 
Distribution. Arctic Ocean, North Atlantic, south to Massachusetts 
Bay, Scotland, Denmark, Point Barrow, Alaska, Sitka, Aleutian Islands, 
Plover Bay, East Siberia, eastern part of Straits of Magellan, Patagonia. 
Subgenus Cryptoctenidia Dali, 1918 
Lepeta concentrica Middendorff, 1851 
Sibirisclic Reise, 183; PI. 16, fig. 6. 
Testa extus incrementi vestigiis lamellulosis, erectiusculis, concentricis 
et confertis ornata; vertice subinflexo; intus nitidissima, vernicosa. Long., 
13; lat., 9; alt., 5 mm. (Middendorff.) 
Shell depressed conical, apex directed forward; front slope one-third 
the length of the shell or a little less; surface faintly radiately striate (more 
distinctly so in young specimens), not decussated or granulose; light- 
brownish or greenish tinted. The outline is ovate, a little narrower in 
front; front slope convex. The fine thread-like radiating striae are larger 
on the longer slope of the shell; they are not interrupted by concentric 
growth-lines, the latter being inconspicuous, or sometimes strongly im¬ 
pressed at intervals. Epidermis very thin, yellowish-brown, deciduous. 
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