182 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



edge of the anterodorsal margin is higher than in others. Young 

 specimens (pi. 26, figs. 6, 7) usually are higher in proportion to the 

 length than older specimens. Typically, the ventral line of the pallial 

 sinus becomes confluent with the main pallial line about the middle 

 of the length of the sinus (pi. 24, fig. 7); but in some shells only about 

 two-fifths of the ventral line is confluent with the ventral line of the 

 pallial sinus, and in others almost three-fifths of the line is confluent. 



Yearly growth lines of the Point Barrow shells of this species are 

 less distinct than in some of the other shells. One shell 18 mm. long 

 is at least 2}^ years old, 2 shells 30 mm. and 32 mm. long are at least 

 4% years old, and 1 shell 39 mm. long is over 5 years old. Another 

 shell only 28 mm. long and about 17.3 mm. high appears to be between 

 5 and 6 years old, making approximately the following growth in 

 height each year: first, 4 mm.; second, 3.7 mm.; third, 3.5 mm.; 

 fourth, 3 mm.; and fifth, 3.1 mm. 



Although M. balthica Linnaeus has been reported from this vicinity, 

 fairly intensive work in the area under investigation yielded no speci- 

 mens. The writer believes that the young of M. calcarea have been 

 mistaken for M. balthica. The greater height in proportion to the 

 length in young M. calcarea could account for this misidentification. 



Distribution: Throughout the Arctic and southward to Japan and 

 Monterey Bay in the Pacific and southward to New York and the 

 British Isles and Denmark in the Atlantic. 



Macotna moesta (Deshayes, 1854) 



Plate 21, figttres 1-3; Plate 23, figure 10; Plate 24, figures 1-3 



Tellina moesta Deshayes, 1854, p. 361. 

 Macoma krausei Dall, 1900, p. 322, pi. 4, fig. 8. 

 Tellina {Macoma) moesta Jensen, 1905, p. 345, figs. 4a-c. 



Macoma oneilli Dall, 1919c, p. 20, pi. 2, fig. 1; 1921, p. 47.— Oldroyd, 1924, p. 173, 

 pi. 40, fig. 7. 



Eight adult specimens were dredged: 1 (22.2 mm. long by 14.1 mm. 

 high) at 80 feet on Aug. 21, 1948; 1 (24.4 by 16.7 mm.) at 120 feet 

 on Aug. 9, 1949); 2 (23.8 by 15.6 mm., and 17.2 by 12.1 mm.) at 

 122 feet; 1 (24.3 by 16.4 mm.) at 132 feet; 1 (23.3 by 16.5 mm. at 

 134 feet; 1 (22.6 by 16 mm.) at 138 feet; and 1 (20.8 by 14.6 mm.) 

 at 148 feet. 



Seven smaller specimens and 1 valve that may be the young of this 

 species were collected: 1 at 50 feet on July 26, 1948; 1 and 1 valve at 

 80 feet on Aug. 21, 1948; 4 that washed ashore on Sept. 12, 1949, 

 and 1 on Sept. 19, 1949. These shells range between 10.6 and 16.6 

 mm. in length. 



Other material examined: Dall's cotype of M. oneilli from Dol- 

 phin and Union Straits, Northwest Territories; 3 from Winter Harbor, 



