DALL: MOLLUSCA AND BRACHIOPODA. 355 
even more angular dorsally, has the posterior mucro nearer to the posterior mar- 
gin, and has the lateral areas of the intermediate valves prominently concentrically 
rippled. 
Lepidopleurus incongruus Da tt, n. sp. 
Animal with the gills forming a very short posterior row; girdle narrow with 
extremely minute, close-set spines, giving the effect of a naked, velvety surface. 
Intermediate valves pale brown, the median line slightly obtusely angular; 
jugum slightly mucronate behind, the jugal area sculptured with very fine, close- 
set, rounded, longitudinal threads; pleural tracts with ten or twelve larger threads 
with wider, flat interspaces, the threads sometimes breaking off abruptly, leaving 
a double-width interval the rest of the way; lateral areas prominent, very finely 
granulose, conspicuously concentrically rippled; anterior plate with feeble con- 
centric ripples and similar granulation; posterior valve with prominent subcentral 
mucro, the central area sculptured like the pleural tracts of the preceding valves, 
the posterior area like the anterior valve; penultimate valve with a length of 2.3, a 
width of 6.0, and an altitude of 2.5 mm. Articulations as usual in the genus. 
U.S. 8. “ Albatross,” station 3354, Gulf of Panama, in 322 fathoms, mud, 
bottom temperature 46° F. U.S. N. Mus. 122,969. 
This species appears to have a unique sculpture. An examination of the valves 
figured in Pilsbry’s monograph for the whole family reveals noue like it. 
Lepidopleurus luridus Dat. 
Lepidopleurus luridus Dall, Proc. U. S. Nat. Mus., 1902, 24, p. 556. 
U.S8.S. ‘ Albatross,” station 3392, in Panama Bay, in 1270 fathoms, hard 
bottom, temperature 36°.4 F.; and station 3393, in 1020 fathoms, mud, temper- 
ature 36°.8. U.S. N. Mus. 109,027. 
Lepidopleurus farallonis Dau. 
Lepidopleurus farallonis Dall, Proc. U. S. Nat. Mus., 1902, 24, p. 557. 
U. S. 8S. “Albatross,” station 3104, near the Farallones Islands, off San 
Francisco, California, in 391 fathoms, coral, bottom temperature 41° F.; U.S. 
N. Mus. 109,025; and at station 3393, Panama Bay, in 1020 fathoms, mud, 
temperature 36°.8 F. 
Mesochitonia. 
Chitonidae. 
CALLISTOCHITON Carpenter. 
Callistochiton periconis Datt, n. sp. 
Animal small, of a pale brownish color with a narrow dark girdle covered with 
small, closely packed setose scales; middle valves with the sculpture of C. pulchellus 
