Il8 ALASKA GEOLOGY 



GASTROPODA 



Chrysodomus sp. 



Tritonium sp. GREWINGK, Beitrag NW. Am., p. 290, 1850. 



Locality. Popof Island, 3372; Makushin Bay, Unalaska (Gre- 

 wingk) . 



Very poor casts of a species resembling C. fornicatus Gray were 

 obtained. 



Chrysodomus sp. 



Locality. Popof Island, 3563. 



A slender species with strong spiral ridges resembling C. liratus 

 Martyn was obtained, in fragmentary specimens. 



Tritonofusus sp. 



Locality. Popof Island, 3372, 3563. 



Fragments of a species recalling T. stimpsont Morch were ob- 

 tained. 



Volutharpa? sp. 



Locality. Popof Island, 3372. 



A poor cast of what may be a Volutharpa or a short stout J3uc- 



cinum was obtained. 



Buccinum? sp. 



Locality. Popof Island, 3372. 



A specimen containing in a very tough matrix the five upper whorls 

 of what may be a small species of Buccinum was collected. The 

 nuclear whorls are smooth, the later ones sharply evenly spirally 

 grooved with about three channels to the millimeter, and, on the 

 shoulder, a succession of short low nodulous waves axially directed. 

 The suture is appressed but distinct. The height of the specimen 

 visible is about 8 mm. and the maximum diameter 7 mm. 



Trochita alaskana sp. nov. 



pi. x, figs. 2, 6. 



Shell of moderate size, and about four convex whorls separated by 

 a well-defined suture, beneath which they are sometimes a little con- 

 stricted, but always more or less convex, with the surface obliquely 

 and rather irregularly striated ; individuals vary in form from quite 

 elevated to moderately conical ; the periphery of the whorl is at the 

 same time the periphery of the base, there being no overhanging 

 margin or keel as in Calyptrcea; base smooth, concave, the umbilical 

 region imperforate or covered by the reflexed columellar margin; 



