CLASS GASTROPODA 
267 
This very remarkable species is very prettily marbled with olive, chest¬ 
nut, and blue; the girdle generally dark olive, dashed with ashy spots and 
in fine specimens having a pubescent appearance. The slit is occupied by 
a cartilaginous substance of a dark brown color, most visible from within. 
(Tryon and Pilsbry, Manual of Conchology.) 
Type in Academy, St. Petersburg. Type locality, Insulae Scantar et 
Sinus Tuguricus maris Ochotici, .... Ins. Sitka, Alaska. 
Range. Shantar Bay, Okhotsk Sea; Bering, Pribilof, and Aleutian 
Islands, and south to Cape Fox, Alaska. 
Described as Chiton brandtii. 
Family ISCHNOCHITONIDAE 
Genus ISCHNOCHITON Gray, 1847 
Valves external, having sharp, slit, insertion plates, the teeth not but¬ 
tressed. Eaves solid (rarely somewhat porous in s. g. Trachydermon) ; 
girdle covered with imbricating scales, either flat or convex, smooth or 
striated. Gills typically extending the entire length of the foot, but in 
some species they are short in front or at both ends. (Tryon and Pilsbry, 
Manual of Conchology .) 
Type. C. longicymba Blainville. 
Distribution. New Zealand, Australia, Japan, West Indies, Cape of 
Good Hope, west coast of North and South America. 
Subgenus Stenoplax 
Ischnochiton fallax Carpenter, 1892 
Tryon and Pilsbry, Manual of Conchology, 14:59; PI. 16, figs. 17-18. 
Almost exactly like Ischnochiton magdalenensis in form and sculpture, 
but more roseate; the central areas pitted; lateral areas having close radi¬ 
ating wrinkles interrupted by lines of growth. Interior: Posterior valves 
having 9, central 1, anterior 10 slits; teeth acute; eaves conspicuous; sinus 
moderate, scarcely laminate, but the jugal part of the valves produced 
forward. Girdle having very minute granules. Length, 27; breadth, 
12J4 mm.; divergence 120°. (Tryon and Pilsbry, Manual of Conchology.) 
Type in ? Type locality, Monterey, California. 
Range. Vancouver Island to Todos Santos Bay, Lower California. 
Ischnochiton biarcuata Dali, 1903 
Proceedings of the Biological Society of Washington, 16:176. 
Animal about 18 mm. long and 7 mm. wide (in the dry state) ; girdle 
narrow, with very small, close-set, more or less imbricating, brownish 
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