322 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
part surrounding the valves being thick, harsh, cartilaginous. The 8 
valves are white and very fragile, the first being nearly horse-hoof shaped, 
crenulated on the front margin; the intermediate valves are shaped as if 
made of two circular disks, and have a transverse obsolete swelling above. 
The first seven valves have a pentagonal sharply margined piece (teg¬ 
mentum), truncated behind, at the angle of the posterior sinus. The eighth 
valve is angular, as if formed of two pentagons, excavated behind. (Tryon 
and Pilsbry, Manual of Conchology.) 
Type in Academy, St. Petersburg? Type locality, Kuril Islands. 
Range. Kuril Islands, and Northern Japan to the Farallon Islands, 
California. 
Amicula vestita Sowerby, 1829 
Journal of Zoology, 4:368. Conchological Illustrations, Chiton; fig. 128. Tryon and 
Pilsbry, Manual of Conchology, 15:43; PI. 8, fig. 
Ch. valvus reniformibus, membrana coriacea vestitus, apocibus nudis. 
Long., 1% 0 ; lat., % 0 poll. 
The rather elevated points of the valves are alone visible in the living 
animal: but when the coriaceous membrane which covers them is dry, their 
edges are easily traced. Little bunches of brownish hairs are scattered 
over the surface. (Sowerby.) 
Oval, rather elevated, the valves nearly covered by a brown (or when 
young) skin continued upward from the girdle, but their outlines are 
plainly visible through this integument. The small exposed portion of each 
median valve is broadly heart-shaped, and situated at the posterior margin 
of the valve; it is sculptured with strong concentric grooves and a more or 
less distinct granulation. There is no differentiation into areas. The ex¬ 
posed portion of the posterior valve is heart-shaped, with the mucro incon¬ 
spicuous, near but slightly behind the middle. Interior pure white. An¬ 
terior valve having 6-8 irregularly spaced and unequal slits ; posterior valve 
having a deep sinus behind, and a single small mopaloid slit on each side. 
Jugal sinus rather small; sutural laminae rather less projecting forward 
than the posterior rounded lobes on each side. Girdle thin, smooth; adults 
generally having more or less developed, but always sparsely scattered, 
small bunches of hairs. Length, 50; breadth, 35 mm. (Tryon and Pilsbry, 
Manual of Conchology .) 
Type in Zoological Society, London. Type locality, Arctic. 
Range. Arctic Ocean and Bering Sea south to Bering, Pribilof, and 
Hagemeister Islands. On the Atlantic south to Cape Cod. 
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