Long. 0·30, lat. 0·18; div. 90°.
Hab. Catalina Island, 10-20 fm., Cooper.
The appearance of this northern genus among the Mopaliæ and Ischnochitons is very remarkable; as is the character of the mantle-margin.
Genus Nacella, Schumacher.
Nacella (? palleacea, var.) triangularis, Cpr. State Coll. No. 416c.
N. t. “N. palleacea” simili, sed multo minus elongatâ; apice elato, marginibus rectangulatim divergentibus; albidâ, maculis fuscis perpaucis ornatâ; striulis subobsoletis.
Long. 0·28, lat. 0·12, alt. 0·18, div. 90°.
Hab. Monterey, 4 dredged dead, Cooper.
Probably a distinct species. The solitary shell sent by Dr. Cooper is shaped like a right-angled triangle, with five large brown spots near the base.