284 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
of small but rather similar spinules; the ends of the large spines, when 
worn flat, have a pavement-like aspect; back not keeled, but rather steeply 
rounded; gills ambient; intermediate valves with a dorsal angle of about 
90°, the lateral areas prominent, with about five radial riblets in each, 
divaricating to seven or ten at the girdle margin, and cut into beads by 
numerous fine concentric furrows; pleural areas and jugum hardly dif¬ 
ferentiated, sculptured with fine, slightly irregular, longitudinal wrinkles, 
finer mesially, crossed by inconspicuous, less elevated, transverse lines; 
anterior valve with fine, beaded, divaricate radial riblets, the insertion 
plates and eaves very short, smooth, not spongy, with about 17 slits; the 
posterior valve with a small, low, subcentral mucro, from which two 
elevated lines extend to the margin, one on either side, forming two areas, 
and from which the wrinkled sculpture, less prominent on the anterior 
area, diverges; posterior slits about 15, lateral slits 2; sinus rather wide, 
entire; pleural laminae rather wide and short. Long, of animal, about 25; 
lat., 15; alt., 6 mm. (Dali.) 
Type in United States National Museum, No. 109024. Type locality, 
U.S.S. “Albatross” Station 3104, off Farallon Islands, in 391 fathoms. 
Range. Known only from type locality. 
Ischnochiton golischi Berry, 1919 
Lorquitiia, January 1919. 
Shell small, strongly carinate, side-slopes faintly arcuate. Surface 
minutely granulose. Head valve with about 45 nearly obsolete ribs, weakly 
grooved between, each bearing 5-7 extremely minute distant granules. 
Median valves with lateral areas distinctly raised, each with 4-5 almost 
obsolete, minutely, distantly, granose ribs; central areas on each side with 
about 20 granulose longitudinal riblets, finer and closer toward the jugum, 
their interstices granulose but scarcely latticed. Tail valve with perhaps 30 
indistinct radiating ribs on the posterior tract. Dorsal girdle scales finely, 
distinctly striate. Color of the shell warm brownish rosy. (Berry.) 
Type in Berry Collection. Type locality, off Santa Monica, California, 
in 100 fathoms. 
Range. Known only from type locality. 
SECTION RHOMBOCHITON Berry, 1919 
Ischnochiton regularis Carpenter, 1855 
Proceedings, Zoological Society of London, 232. Tryon and Pilsbry, Manual of Con - 
chology, 14:142; PI. 18, figs. 41-46. 
C. t. elongata, elevata (ad angulum 110°), fusco-olivacea, jugo acuto; 
valvis intermediis lineis diagonalibus haud conspicuis; areis lateralibus et 
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