MARINE MOLLUSKS — MACGINITIE 85 



shouldered slope and the spiral bands begin at the slight angle. 

 There is some variation in the number of sph'al bands and in the 

 width of the incised line between them. 



Dr. Thorson compared these specimens with Moller's types. He 

 states that the structure of these shells is quite identical with those 

 of the types, but that in the type of C. castanea the last whorl is 

 somewhat broader and the shell is somewhat larger than the ones 

 from Point Barrow. These differences seem to agree with Ball's 

 description of the differences between typical C. castanea and his 

 variety alaskana in which he states that the latter has the same number 

 of whorls as the typical form but is only five-eighths the length of 

 typical C. castanea, and is much thinner than typical C. castanea 

 generally is. Dall also says that in var. alaskana the wi-inkles 

 extending forward from the sutures are more prominent than in 

 typical C. castanea. 



The specimen from 184 feet, taken on Aug. 30, 1949, has at least 13 

 large eggs or embryos on its body, indicating that it is an ovoviparous 

 species. 



Distribution: Point Barrow; and (Thorson, 1944) Grinnell Land 

 and Newfoundland to Cape Cod, eastern and western Greenland; 

 northern and eastern Iceland, Spitzbergen, and northern Norway. 

 C. castanea has not been reported from the western Arctic. 



Genus Alvania Risso, 1826 



Alvania jan-mayeni? Friele, 1886 



Rissoa (Alvania) jan-mayeni Friele, 1886, p. 27, pi. 11, figs. 6, 7. 



Alvania jan-mayeni Morris, 1947, p. 108, pi. 39, fig. 14; 1951, p. 145, pi. 39, fig. 14. 



A single living specimen was collected at 741 feet on Aug. 17, 

 1949. 



Discussion: The shell, which was about 1.8 mm. long, was tan, 

 with 2 reddish tan, beaded cords per whorl. The oval, yellow 

 operculum consists of an acentric nucleus uath two spirals. The 

 shell, which was somewhat broken, subsequently dissolved, leaving 

 the body and operculum of the animal. 



Dr. Thorson, who examined the fragmentary shell, says that the 

 color and the size and structure of the apex agree well with living 

 specimens from eastern Greenland, but the condition of the shell 

 renders positive identification impossible. 



Distribution: Point Barrow; and (Thorson, 1944) Newfoimdland 

 to Cape Cod, eastern and western Greenland; Jan May en, and Spitz- 

 bergen. 



