92 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io» 



The largest shell is 19.3 mm. in diameter, the smallest about 13.5 mm. 

 Two empty shells were also taken. 



Other material examined: The type, from Captain's Harbor, 

 Unalaska Island, in the Aleutians; and about 10 specimens from the 

 following localities: Kotzebue Sound, near the Pribilofs, Amchitka 

 Island in the Aleutians, and southeast of the Alaska Peninsula. 



Discussion: Time did not permit a thorough study of other north- 

 ern species of Polinices, but it is obvious that P. gronlandicus and P. 

 pallidus, especially the young, have been confused with P. monteronus. 

 In most specimens of the latter, the umbilicus is almost or completely 

 closed by the callus and the enamel of the inner lip, but in others the 

 umbilicus is scarcely concealed at all. In some young specimens of 

 P. pallidus the umbilicus is partially covered with enamel in such a 

 manner that it closely resembles the notched callus of specimens of 

 P. monteronus with the more open umbilicus. When a specimen of 

 P. pallidus with this type of callus also has an unusually short spire, 

 it is easily confused with P. monteronus. In such instances, the greatly 

 thickened pillar lip of P. monteronus is diagnostic, for it is about twice 

 as broad as that of P. pallidus (see pi. 12, figs. 9, 10). As in the pre- 

 ceding species, the nucleus and the postnuclear whorl are nearly always 

 eroded. 



Distribution: Point Barrow south to Amchitka Island (about lat. 

 52° N.) in the Aleutians, and east and north to Prince William Sound. ^ 

 It has not been reported previously from north of Kotzebue Sound. 



Family Lamellariidae 



Genus Onchidiopsis Bergh, 1853 



Onchidiopsis glacialis (M. Sars, 1851) 



Lamellaria glacialis M. Sars, 1851, p. 185. 



Onchidiopsis glacialis G. Sars, 1878, p. 153, pi. 12, figs. 6a-c. — Odhner, 1913, 

 p. 73, pi. 2, figs. 17, 18, 23, 24; pi. 5, figs. 3, 5, 32, 33. 



In the open season of 1949, 15 specimens washed ashore: 2 in July, 

 3 in August, and 10 in September. One was dredged at 420 feet in 

 August, and another at 453 feet in October. The largest of these, 

 washed ashore in July, measured, when crawling, 34 mm. long, and the 

 foot extended posteriorly beyond the body an additional 10 mm. The 

 tentacles were 11 mm. long, the siphon 7 mm. long, and the largest 

 tubercles were about 5.5 mm. high. When preserved, this same ani- 

 mal measured about 29 mm. long, 18 mm. wide, and 13.5 mm. high. 

 After preservation, the smallest specimen, dredged in October, meas- 

 ured 18 by 12 by 10 mm. The shell from a somewhat contracted 



• For more detailed locality records for many of the West Coast species, the reader is referred to Burch 

 (1945-1946). 



