CALLISTOCHITON. 267 



C. JACOB^EUS Gould. Unfigured. 



Shell small, ashy, elongated, elliptical, hardly carinated ; end 

 valves very large, vaulted, ornamented with 10 scaly radiating ribs; 

 central areas cancellated ; lateral areas conspicuous, bicostate. 

 Ligament narrow, covered with minute elongated scales. 



Length 12, breadth 5 mill. (Old.} 



Interior: posterior valve having 7, anterior 10, central 1 slit; 

 teeth acute, curved outwardly ; eaves solid ; sinus wide, nearly flat, 

 laminate, the lamina more or less separated from the sutural plates 

 [by notches at the sides of the sinus]. Girdle imbricated with flat, 

 striated scales. ( Cjpr.) 



Simoda, Japan (North Pacific Expl. Exped.) 



C. (Leptochiton) Jacobceus GLD., Proc. Boston Soc. Nat. Hist. vii,. 

 p. 164 (Dec., 1859) ; Otia Conch., p. 117. Callistoehiton jacobceus 

 CPE., MSS. 



Carpenter gives the following notes ; but it must be remembered 

 that his C. pulchellus is not the true pulchellus of Gray. 



" If this shell had come from Central America, I should certainly 

 have regarded it as C. pulchellus with which it exactly agrees in 

 sculpture, number of ribs, size andstriation of the scales, and general 

 aspect. Indeed it can scarcely be separated as a variety, like the 

 Californian shell. Inside, however the teeth are somewhat sharper,, 

 one of them having an extra slit. The lamina which lines the sinus 

 is very thin and sharp, generally (but not always) marked off' from 

 the sutural plates by slight slits. In some valves, the lines which 

 mark it off* are perceptible, but they do not serrate the edges. It is- 

 also much broader in some valves than others. Whether the species 

 are or are not identical, cannot be decided from the single specimen 

 in the Smithsonian Museum. It is very singular that a shell from 

 equatorial S. America should be replaced by a very distinct species 

 in the Bay of Panama, should reappear in the Gulf of California, be 

 still found in the temperate seas of California and lastly display a 

 representation on the shores of Japan." ( Cjpr.) 



C. ELENENSIS Sowerby. PI. 59, figs. 27, 28. 



Shell oblong, pallid ; back rounded ; anterior valve radiately sul- 

 cate ; lateral areas of the intermediate valves swollen, unisulcate ; 

 posterior valve retuse, radially sulcate behind ; central areas of the 

 intermediate valves irregularly sulcate-scabrous ; margin smooth. 



Length *6, breadth '3 inch. (Sowb.~) 



St. Elena and Panama. 



