282 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
with small imbricating, deeply striated scales. Length, 40; breadth, 24 mm. 
(Pilsbry.) 
Type in Academy of Natural Sciences, Philadelphia, No. 118659. Type 
locality, Bolinas Bay, California. 
Range. Mendocino County to Catalina Island, California. 
Ischnochiton cooperi acutior (Carpenter MS) Dali, 1919 
Proceedings of the United States National Museum, 55:508. 
On comparing specimens named by Carpenter in the collection of the 
United States National Museum, the only differences I could perceive 
were that the specimens of the variety acutior were lighter and brighter 
in color, more emphatic in sculpture, and apparently younger shells. In a 
group where color is often without systematic value, these differences 
seem hardly worthy of a name, analogous mutations being most common 
among Chitons. (Dali.) 
Type in United States National Museum. Type locality, Lower Cali¬ 
fornia. 
Range. San Diego, California, to Las Animas Bay, Lower California. 
Ischnochiton clathratus Reeve, 1847 
Conchologia Iconica, Chiton, PI. 18, fig. 113. Tryon and Pilsbry, Manual of Con- 
chology, 14:128; PI. 26, figs. 31-34. 
Chit, testa ovata, elevatiuscula, valvis terminalibus caeterarum areisque 
lateralibus radiatim rugoso-granatis, centralibus peculiariter crebriclathra- 
tis; nigricante-viridi; ligamento subtiliter granoso-coriaceo, obscure tes- 
sellato. 
Shell ovate, rather elevated, terminal valves and lateral areas of the 
rest radiately roughly grained, central areas peculiarly closely latticed; 
blackish-green; ligament finely granosely coriaceous, obscurely tessellated. 
(Reeve.) 
Type in Museum Cuming. Type locality, not given. 
Range. Bolinas Bay, California, to Gulf of California. 
Described as Chiton clathratus. 
Ischnochiton decipiens Carpenter, 1892 
Tryon and Pilsbry, Manual of Conchology, 14:123. 
Shell exactly like I. pectinulatus, but reddish, elevated, the jugum 
acute; scales of the girdle small, striated. Length, 15; breadth, 7y 2 mm.; 
[884] 
