186 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io» 



than that of M. truncata and always is sufficiently long that a vertical 

 line from the beaks cuts across it, whereas in M. truncata the sinus 

 may or may not extend to such a vertical line. The ventral scar of 

 the pallial sinus of M. arenaria is above and separate from the main 

 pallial scar (pi. 25, fig. 5), whereas in M. truncata these scars are 

 either contiguous or confluent throughout most of the length of the 

 sinus (pi. 25, figs. 1-3). 



Distribution: M. truncata extends from Point Barrow south and 

 east to Puget Sound; on the east coast from Greenland to Massa- 

 chusetts (Johnson, 1934); Norway, Iceland, the Shetlands, and Eng- 

 land. The var. uddevallensis has been collected at Point Barrow 

 (G. E. MacGinitie, 1955), at Afognak and Raspberry Islands (near 

 Kodiak Island), and in Sweden (W. J. Eyerdam) (see Burch, 1945, No. 

 44, p. 25) ; in Norway and Iceland and southward to the Bay of Biscay 

 (see Madsen, 1949, p. 77). Point Barrow is a new locality for var. 

 uddevallensis. 



Mya pseudoarenaria Schlesch, 1931 



Plate 19, figure 7; Plate 25, figure 4 



Mya intermedia Dall, 1898, p. 857 (in part). 



Mya truncata forma ovata Jensen, 1901,>5 pp. 139, 144, figs. 3-5, 6a-c (not M. 



ovata Donovan, 1802). 

 Mya pseudoarenaria Schlesch, 1931, p. 136, pi. 13, figs, 10-12. — Soot-Ryen, 1951, 



p. 3. 



About 16 specimens were collected: Between Aug. 21 and Sept. 24, 

 1949, 4 specimens (from 23 to 67 mm. long) washed ashore; on Aug. 23, 

 1950, 1 specimen (31 mm.) washed ashore; 3 specimens and 5 valves 

 (from 43 to 66 mm.) were dredged at Eluitkak Pass on Aug. 6, 10, 1948; 

 3 specimens (about 11 mm.) were dredged at 10 feet on Oct. 11, 

 1949; 1 (about 12 mm.) at 120 feet on Sept. 15, 1948; 

 1 shell (16 mm.) at 120 feet on Aug. 8, 1949; and 2 shells (13 and 14 

 mm.) and 1 living specimen (14 mm.) at 162 feet on Feb. 18, 1950. 

 Specimens that washed ashore were often still alive. 



Other material examined: Numerous specimens of M. ^'inter- 

 media" from the Probilofs, the Aleutians, and Kamchatka; speci- 

 mens of M. truncata forma ovata from Greenland; several specimens of 

 M. japonica Jay from Japan and Puget Sound; also specimens of M. 

 arenaria from the Atlantic and Pacific coasts. 



Discussion: It is now generally conceded that all recent records of 

 living M. arenaria Linnaeus (1758, p. 670) in the Arctic are of some 

 other species. Dall (1898), realizing that a Mya from Alaska belonged 

 neither to M. truncata nor to M. arenaria, described it as a new species 

 under the name intermedia — a name that was later found to be pre- 



'* The date for this form. Is usually given as 1900 The volume was for the year 1900, but It was published 

 In 1901 



