NO. 1264. ILL USTBA TIONS OF AMERICAN SHELLS— BALL. 557 
iirrangeineiit of the pu.stulos on the jugum; the ctenidia only reach 
the seventh valve. Lon. of animal about 16; lat. H; alt. 8 mm. 
Dredged in Panama Bay by the IT. S. Fish Commission steamer 
Alhatross, at station 3393, in 1,020 fathoms, mud, bottom temperature 
36.8° F.; U.S.N.M., 109027. 
In the solidity of its valves, its mucronate jugum, and the arrange- 
ment of the pustular sculpture this seems sufficiently distinct from any 
of the described species. 
LEPIDOPLEURUS FARALLONIS, new species. 
Chiton small, thin, wide, with a low rounded back and yellowish-white 
color; girdle narrow, sparsely spiculose, with very short, tine, bristly 
spicules; jugum hardly defined, with no obvious mucro; lateral areas 
slightly elevated and feebly concentrically rugose; anterior valve sim- 
ple; posterior conspicuousl}' mucronate and, behind the mucro, con- 
cave; surface entirel}^ covered with minute, low, close-set pustules, 
arranged quincuncially and to some extent concentrically from the 
nuicronal points; pleural lamin;e short, subtriangular; ctcnidial line 
reaching the fifth valve. Lon. of animal about 10; lat. 5.5; alt. 2 mm. 
Dredged ])y the U. S. Fish Connnission steamer AlhatrosH otf the 
Farallones Islands, near San Francisco, California, at station 3104, in 
391 fathoms, coral, bottom temperature 41° F.; U.S.N.M., 109025. 
This little species has no very striking characters, but, having been 
compared with all the boreal and Pacific species hitherto recorded, it 
was found not to be identical with an}^ of them, 
ISCHNOCHITON STEARNSII, new species. 
Chiton of moderate size, yellowish or buff color; the girdle yellowish- 
white, covered with subcylindric, blunt, smooth, close-set, large spines, 
the ends of which have a pebbly appearance, mixed with a smaller pro- 
portion 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 ril)lets in each, divaricating to seven or ten at the girdle margin, 
and cut into l)eads by numerous fine concentric furrows; pleural areas 
and jugum hardly differentiated, sculptured with fine, slightly irregu- 
lar, longitudinal wrinkles, finer mesially, crossed by inconspicuous, 
less elevated transverse lines; anterior valve with fine, beaded, divari- 
cate radial ril)lets, 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 
