190 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



One living specimen was taken at Eluitkak Pass on Aug. 1, 1950, and 

 1 right valve was dredged at 184 feet. The former shell is 68 mm. 

 long and 44.5 nmi. high and the latter is 54 by 40 mm. 



Other material examined: The figured type from Kyska Harbor, 

 and about 20 other specimens from Nunivak Island, Kodiak Island, 

 Kyska Island, and Unalaska Island. 



Discussion: The shells of this species are usually flat but they vary 

 from flat to somewhat inflated. The younger specimens tend to be 

 flatter in proportion than the larger ones. There is also variation in 

 the thickness or heaviness of the shells. 



The shell of P. ampla is tapered anteriorly and flared posteriorly, 

 and the posterior margin is obliquely truncate in such a manner that 

 the basal line recedes (pi. 25, fig. 7). Oldroyd's (1924) figure 3 of 

 plate 10 is of P. turgida (=P. arctica) and not of P. ampla as stated. 

 This error has been repeated in several subsequent publications; the 

 figures in the foUowing references should read P. arctica instead of 

 P. ampla: Grant and Gale (1931, pi. 21, figs. 10a, 10b); Morris (1952, 

 pi. 16, fig. 8); and Kha (1954, pi. 61, fig. 17). 



Distribution: The range of P. ampla has been given as the 

 Aleutian region (see localities above) to Puget Sound but the latter 

 locality record has been questioned. In the collections of the U. S. 

 National Museum I saw no specimen of P. ampla from Puget Sound. 

 The present range, therefore, is from Point Barrow to Kodiak Island, 

 Alaska. It is new to Point Barrow and to Arctic America. 



Genus Hiatella Daudin, in Bosc, 1801 

 Hiatella arctica (Linnaeus, 1767) 



Plate 26, figures 1-3 



Saxicava arctica Linnaeus, 1767, ed. 12, p. 1113. — Oldroyd, 1924, p. 208, pi. 9, 

 fig. 6; pi. 51, fig. 4.— Morris, 1947, p. 67, pi. 23, fig. 5; 1951, p. 91, pi. 23, fig. 5; 

 1952, p. 62, pi. 16, fig. 7. 



This was the most abundant bivalve and, with the exception of 

 barnacles, probably the most abundant and the most nearly ubiquitous 

 animal in the area under investigation. Probably no haul except 

 from the strictly muddy bottoms near shore was without representa- 

 tives of H. arctica. Even near shore in the gravel zone, they were 

 found anchored to bits of gravel or old shells. Two specimens (4.5 

 and 5.5 mm. long) from 184 feet were found growing on the bryozoan 

 Truiellaria erecta, and 2 others (5 and 6 mm.) from 341 feet were 

 growing on the bryozoan Eucratea loricata. They were found between 

 barnacles, in old clam shells, and among old holdfasts. In addition to 

 3 or 4 barnacles, an old shell of Astarte borealis contained 21 living 



