320 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Type in British Museum. Type locality, west coast of North America. 
Range. Western and southern Bering Sea, to Cook’s Inlet, Alaska, 
and south to Catalina Island, California. 
Described as Chiton tunicata . 
Family CRYPTOCHITONIDAE 
Genus CRYPTOCHITON Middendorff and Gray, 1847 
Valves entirely concealed in the leathery girdle, and lacking tegmentum; 
their posterior margins produced backward in a deep lobe on each side, 
the lobes united across the median line, causing the apices of all valves to 
be removed inward from the posterior edge. Slits subobsolete or lacking 
in the intermediate valves. Girdle covered with minute tufts of short 
bristles. Gills extending the entire length of the foot. (Tryon and Pilsbry, 
Manual of Conchology .) 
Type. Cryptochiton stelleri Middendorff. 
Distribution. West coast of America and Japan. 
Cryptochiton stelleri Middendorff, 1846 
Chiton amiculatus (Sowerby and Reeve) minime vero Pallasii. Chiton 
gigas ovatus dorso rotundato, testa interna valvis fragilissimis aditu nullo 
abditis, incarceratis in pallio totum corpus ambiente coriaceo, obtecto epi- 
dermide ex ferrugineo lutescente, pustulis confertis subverrucosa. Epi- 
dermidis pustulae apertae (nisi summo apice per se perforatae) sublente 
seterum rubrarum confertissimarum exhibent fasciculos internos. 
Valvae planiusculae omnes incrementi umbone vix perspicuo subcentrali. 
.... Valva prima dentibus quinque latis in margine antico. 
Valva secunda et ultimo utrinque incisura laterali.Valva ultima 
postice emarginata bidentata. Branchiarum series ab initio secundae quar- 
tae partis ad finem septimae octovae partis longitudinis totius corporis 
porrectae. Lamellarum branchialium numerus circiter 70.Adulti 
longitudo, 1.9 decim. (Middendorff.) 
Diese Species kann unmoglich mit irgend einer andern verwechselt 
werden, und begriindet sogar durch ihre Eigenthumlichkeiten ein neue 
Untergeschlecht. Middendorff. 
Oblong rather depressed, the bilobed posterior outlines of the valves 
(in dry specimens) showing through the leathery integument, which com¬ 
pletely covers the valves. Color a dull ferruginous or brick-red, very well 
[ 922 ] 
