MARINE MOLLUSKS — MACGINITIE 133 



in the collection of the U. S. National Museum. The columellas of the 

 Point Barrow specimens appear straighter than in species No. 135. 

 Distribution: Point Barrow and southward. 



Obesotoma simplex (Middendorflf, 1849) 

 Plate 16, figure 2 



Pleurotoma simplex Middendorflf, 1849b, p. 19; 1849c, pt. 2, p. 119; 1849d, pt. 2, 



p. 448; 1851, vol. 2, pt. 1, p. 223, pi. 12, figs. 15, 16. 

 Beta simplex G. Sars, 1878, p. 239, pi. 17, fig. 4; pi. 23, fig. 11. 

 Bela ? laevigata Dall, 1871, p. 98, pi. 16, fig. 7. 

 Bela laevigata Dall, 1886, p. 300, pi. 3, fig. 7. 



Four specimens were washed ashore: 1 dead (11.6 by 6 mm.) on 

 Sept. 12, 1 living (11.5 by 6.1 mm.) on Sept. 23, 1949; and 2 living 

 (11.6 by 7.2 mm. and 11.7 by 6.3 mm.) on July 26, 1950. 



Other material examined: The type of B. laevigata, from St. 

 Michael, Alaska, 35 specimens from Norton Sound, and 20 specimens 

 from Chirikoff Island; and (labeled B. simplex) 2 large specimens from 

 Spitzbergen, 6 (from small to large) from Norway, and 2 large speci- 

 mens from Russian Lapland. 



Discussion: Although Sars examined specimens of this species from 

 the Pacific and identified them as B. simplex, Dall believed they were 

 sufficiently different to warrant a new species and he described them 

 as B. laevigata. That Sars considered this a highly variable species 

 is shown by his two figures (as listed in the synonomy above). After 

 examining one of the specimens in the MacGinitie collection, Dr. 

 Thorson wrote me that it agrees closely with some of the specimens 

 from eastern Greenland. He added that it is an extremely variable 

 species. Something of the variability in proportions is illustrated 

 by the measurements given above. 



Although it was a living specimen, the shell taken on September 

 12 is deeply pitted and the spire is badly eroded (pi. 16, fig. 2). The 

 outer lip is broken and the shell shows two previous breaks along 

 old lip lines. 



Distribution: Point Barrow to Chirikof Island (about lat. 55.5° 

 N. and long. 155.5° W.) and the Sea of Okhotsk; and (Thorson, 

 1944) eastern Greenland, northern and eastern Iceland, Spitzbergen, 

 and northern Norway. 



Obesotoma sp. 3 



Two living specimens of this species were dredged: 1 (13.7 by 7 

 mm.) at 341 feet and 1 (11.1 by 5.9 mm.) at 741 feet. 



Discussion: These two specimens are the same as Bartsch's 

 manuscript species No. 232, of which there is one somewhat worn 

 specimen (from southeast of Kamchatka) in the collections of the 

 U. S. National Museum. 



Distribution: Point Barrow, Alaska, to southeast of Kamchatka. 



