PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 341 



Acmaea (Collisella) peramabilis. 



A. peramabilis Dall, Proc. Cal. Acad. Sci. iv, p. 302, Dec. 1872. 



Hal). — Shumagin Islands, low water to six fathoms. Six specimens. 



This most lovely species is most like some reddish varieties of patina, 

 but none of them approach it in color, while numerous other features 

 testify to its distinctness; which I have, as yet, seen no reason to doubt. 

 It appears to be exceedingly local and rare, but all the specimens pre- 

 sent a very uniform appearance. 



Acmaea (Collisella) sybaritica. 



Collisella sybaritica Dull, Am. J. Conch. 1. c. vi, p. 257, pi. 17, f. 34 a-c, 1871. 



Hal). — Pribiloff Islands southward on the west to Hakodadi, Japan 

 (Stm.!), throughout the Aleutians, and on the southeast to Chirikoff 

 Island, and perhaps Kadiak ; from lowest water to twenty-five fathoms. 

 One hundred and ninety specimens examined. 



This beautiful little species, of which only a few specimens were 

 known when it was described, has since been found over a very large 

 area, and usually in rather deep water for the genus. It seems to rep- 

 resent Acmcva virginea on the Pacific side, though not very similar to it 

 in appearance. The largest specimen found is an inch in length, but 

 they are always very much flattened. 



Acmaea (Collisella?) triangularis. 



Nacella (fpaleacm var.) triangularis Cpr. Proc. Cal. Acad. Sci. iii, p. 213, 1366. 

 Collisella ? triangularis Dall, 1. c. p. 254, 1871. 



Hob. — Sitka to Monterey, Cal. 5 dead on beaches. 



This species varies from narrow, high, and elongated to rounded and 

 rather flat, according to the place of its growth, as on a frond or leaf of 

 some marine plant like Zostera, or on a flat unlimited surface. It ap- 

 pears very rare in Alaska, only one specimen having been collected 

 there, but is tolerably common on the coast of California. I have never, 

 however, been able to get it in the living state, so as to definitely de- 

 cide its generic place. 



Acmaea (Collisella?) apicina n. s. 



Testa parva, conica, tenui, rotundata, plus minusve elevata : albida 

 seu isabellina, apice erecto, luteo ; intus luteo, albido. sen fusco, hevi ; 

 extus striulis incrementis subobsoletis rnunito. Lat. 5 mm., Lou. 6 mm., 

 Alt. 4 mm. 



Hab. — Pribiloff Islands on the north, the Aleutians from Amchitka 

 eastward, extending to the Shumagins; twenty-two specimens, all dead 

 except two, one of which was found at low water and the other dredged 

 in seventy fathoms. 



Among other small shells obtained from time to time on the beach or 

 in the dredge, occasional specimens occurred which at first were sup- 

 posed to be the young of A. mitra or pale specimens of A. sybaritica. 



