MARINE MOLLUSKS — MACGINITIE 125 



Kepositories: Holotype, U. S. National Museum, No. 602,694. 

 Paratypes, U. S. National Museum, Nos. 606,132 (2); 606,136 (1); 

 606,141 (1); 606,142 (3); 606,144 (3); 606,146 (3). Other paratypes 

 in the collections of the California Academy of Sciences, Stanford 

 University, and Zoological Museum, Copenhagen. 



Other localities: Specimens in the U. S. National Museum from 

 the Arctic Ocean and Bering Sea. Also from northern Japan. 



Remarks: In addition to the type, 13 living specimens were dredged: 

 1 (66.5 by 37 mm) at Eluitkak Pass; 1 (39 by 20.5 mm.) at 125 feet; 

 1 (48 by 25 mm.) at 130 feet; 1 (65 by 35 mm.) at 150 feet; 4 (55 by 

 30, 55 by 31, 49 by 27, and 28.5 by 16 mm.) at 152 feet; 1 (69 by 38 

 mm.) at 184 feet; 3 (43.5 by 36, 63 by 32, and 68 by 38 mm.) at 420 

 feet; and 1 (39+ mm. long) at 438 feet. A few more or less broken 

 shells inhabited by hermit crabs were dredged at Eluitkak pass, 110, 

 125, 130, and 150 feet. 



In some specimens of this species from Point Barrow the keel is 

 approximately in the middle of the whorl (pi. 14, fig. 10), and in one 

 or two specimens it is closer to the posterior end of the whorl than to 

 the anterior (pi. 14, fig. 7 shows a specimen in which it is slightly 

 nearer the posterior end). In one specimen (pi. 14, fig. 10) the nodules 

 on the last whorl are rather marked. Some specimens lack the brown 

 border along the inner margin of the external lip, and in immature 

 specimens the entire throat is usually brownish. On the last whorl, 

 especially on the last quarter turn, a few shells develop irregularly 

 spaced longitudinal ridges (pi. 14, fig. 10) ; in such shells the canal, 

 relatively straight in the majority of the shells, is somewhat curved 

 and reflected. 



This species differs from N. heros and A^. ventricosa in its consistently 

 darker color and slender shape, in its shorter and narrower aperture, 

 in its straighter columella, and in its shorter, narrower, and generally 

 less reflexed canal. The nucleus is less tapered than that of A^. heros 

 but usually not so cylindrical as that of A^. ventricosa. The operculum 

 tends to be narrower than that of either of the above species. 



This species is named in honor of A. Th. von Middendorff, who 

 probably first collected an example of the species and who worked on 

 the difficult Arctic neptuneids. 



Discussion: Since Middendorff 's polynomial designation is not 

 acceptable and since Hermann's Bucciniim solvtum (1781) is a Buc- 

 cinum and not a Nepiunea as Dall (1907) thought, it is necessary to 

 assign another name to this species. 



The shell described by Hermann was purchased at an auction in 

 Paris several years prior to the publication of his description and no 

 locality was given. The shell (pi. 27) is obviously a lamellose speci- 



