THE NAUTILUS. 51 



Several valves of a different Tonicia with rugose lateral areas and 

 head valve, lirate pleural tracts, and sparse, excessively minute eyes 

 also occurred. 



Ischnochiton comptus Gld. 



Ischnoehiton Mitsukurii n. sp. 



Shell small, elevated, carinated, the side slopes slightly convex ; 

 whitish, profusely speckled and clouded with brown, which color 

 predominates toward the periphery. 



Valves not beaked, the sutural margins straight ; lateral areas 

 somewhat raised, sculptured with three or four very shallow, incon- 

 spicuous, radial sulci, hardly visible on some valves; the diagonal 

 line not conspicuous ; entire surface cut into a fine, even granulation 

 by the intersection of a series of forwardly converging with some- 

 what stronger forwardly diverging grooves. Anterior valve evenly 

 granular; posterior valve evenly granular, with central, scarcely 

 projecting mucro, the slope behind it straight. 



Interior with the valve callus delicate purple ; in front of it and 

 at the insertion plates green. Sutural laminse small, widely separ- 

 ated by a wide sinus. Slits in valve i, ; in valves ii to vii, 1-1 ; 

 in valve viii, 11. Teeth short, smooth ; eaves narrow and solid. 



Girdle compactly covered with small, rather coarsely striated 

 scales, measuring O14 mm. in average width. 



Length about 8 mm. Angle of divergence 90. 



Japan. Exact locality not known. The name is in honor of the 

 well known Japanese zoologist. 



SOCORRO ISLAND, off Cape St. Lucas. 



A few species were collected by Mr. R. C. McGregor some time 

 ago, and kindly presented to the Academy. 



Chiton articulatus Sowb. Very large specimens, measuring 90 

 mm. long. 



Chcetopleura sp. undet. A species allied to Ch. cohimbiensis but 

 with very few pustules on the lateral areas. The surface having 

 suffered from immersion in strong formalin, it is hardly in condition 

 for description. 



Trachydermon deniiens (Gld.). 



Rather small, black with indistinct dirty yellowish speckling and 

 the usual sutural dots. Gills ambient, 15 on the right, 13 on the 

 left side. Socorro Island lies over 500 miles south of the souther- 

 most previous locality for this species. 



