292 University of California Publications in Zoology (Vou. 14 
and feebly concentrically rugose; anterior valve simple; posterior conspicuously 
mucronate and, behind the mucro, concave; surface entirely covered with minute 
ally from the mucromal points; pleural laminae short, subtriangular; ctenidial 
line reaching the fifth valve. Animal about 10; lat. 5.5; alt. 2 mm.’’ 
Occurrence.—Dredged by the ‘*‘ Albatross’’ off the Farallon Islands 
during a previous survey at station 3104 in 391 fathoms. 
This species has not been reported since it was first discovered. 
ISCHNOCHITONIDAE 
Tonicella Carpenter 
Tonicella lineata (Wood) 
Plate 34, figure 3 
Chiton lineatus Wood (1815), p. 3, pls. 4-6. 
Tonicella lineata Pilsbry (1892-1893), p. 42, pl. 11, figs. 25-28. 
Description.—This species was described by Pilsbry as follows: 
‘*Shell oblong, rather low, roundly arched or subcarinated. Surface smooth, 
shining, ground color light reddish. End valves concentrically marked with 
dark-brown lines bordered above with white, intermediate valves having simi- 
larly colored longitudinal lines, sloping obliquely backward, the ridge or jugum 
of each valve having a light triangle with a narrower dark one in the middle 
on some valves. Occasionally some valves are wholly dark brown unmarked. 
Lateral areas scareely raised; umbo of posterior valve in front of the 
middle. 
Interior white, more or less tinged with rose color. Sutral plates broad, 
rounded; sinus deep and angular. Anterior valve with 8-10, median 1, posterior 
valve 8-10 slits. Teeth short, especially in the posterior valve, and blunt, in 
adults decidedly crenulated at the tips and obsoletely fissured outside. Eaves 
small. 
Girdle leathery, apparently smooth and nude, brown in dried specimens.’’ 
Length, 15 to 20 mm. 
Occurrence —Bonita Point* (3). 
This species is represented in the Survey collections by three speci- 
mens from the shore station at Bonita Point. It had been previously 
been reported from this region by Wood and Raymond. 
Range.—Bering Strait to Monterey, California (Pilsbry). 
Ischnochiton Gray 
Ischnochiton dentiens (Gould) 
Chiton dentiens Gould (1846a), p. 145; (1862), p. 6. 
Trachydermon dentiens, Dall (1878b), p. 823; Carpenter (1863), p. 649. 
Ischnochiton dentiens, Pilsbry (1892-1893), p. 73, pl. 8, figs. 61-65. 
Description—Pilsbry (1892) describes this species as follows: 
‘<Shell oval, rather elevated, dorsally angled, ash colored, closely and finely 
mottled with olive, and having a series of alternating olive and light spots upon 
the back edges of the valves along the sutures. These spots are often obscure 
or wanting, and in some specimens the ground color is a pale orange-flesh tint. 
