It.-:,,. PROCEEDINGS OF THE NATIONAL MUSEUM. 709 



Subgenus ANCiSTROi.Ens, Dall. 



Shell bnccinoid, witli a short twisted canal; operculum straight, claw- 

 shaped, concave, with apical nucleus; penis on a stout stalk with the 

 distal extremity eidarged, foot-shaped, solid, without curved or atten- 

 uated point; dentition like Ghrysodomns ; laterals with a larger outer 

 and two smaller inner curved cusps; median with three rather long, 

 slender, subequal cusps, the anterior edge of the base concavely sinu- 

 ate; the radula disproportionately small. Type Ghrysodomus eucosmhis, 

 Dall. 



This group differs from Ghrysodomus in its shorter canal, peculiar 

 operculum, and degenerate radula; from Liomesus and Beringius in its 

 cuspidate rhachidian tooth and narrow claw-like operculum. It seems a 

 characteristic Aleutian type. 



GHRYSODOMUS (ANCISTROLEPIS) EUCOSMIUS, Dall. 

 Plate XXIX, fig. 7. 



Chrysodovuis eucosmius. Dat>l., Proc. U. S. Nat. Mns., xiv, p. 187, 1891. 



Station 2919, near Cortes Bank, California, in 984 fathoms, mud; 

 bottom temperature 38° F. ; stations 3227 and 3502 north of Unalaska 

 in Bering Sea, in 225 and 3G8 fathoms, muddy bottom; temperature 

 38.6° F., and in several other localities on the Alaskan coast, in 60 to 

 350 fathoms, and off the coast of Oregon and California; south to 

 station 2923, off San Diego, Cal., in 822 fathoms. Ko. 122670, U.S.KM. 



The figured type is only 33 mm. in length, but specimens less well 

 j)reserved reach over 50 mm. The area by which the operculum is 

 attached to the body, as in Strombus, is quite small and the point of 

 the operculum stands off from the body. 



GHRYSODOMUS (ANCISTROLEPIS) MAGNUS, new species. 

 Plate XXIX, tig. 5. 



Station 3254, in Bering Sea north of Unimak, in 46 fathoms, sand; 

 and station 3255, near by, in 43 fathoms, sand; bottom temperature 

 370 F. Nos. 122674 and 12J675, U.S.J^.M. Also near the Pribilof 

 Islands, in 59 fathoms; temperature 35° F. 



Shell rather thin, with six whorls, covered by a thick pilose epidermis; 

 whorls flattened or channeled near the suture and with a single strong 

 keel at the shoulder, the surface covered with fine spiral threads 

 crossed by rather prominent lines of growth,; pillar short, normally 

 much twisted and the coil pervious for one whorl, but some specimens 

 attacked by annelids have it nearly buccinoid ; aperture ample, the 

 body with more or less callus laid over it, the outer lip not reflected; 

 siphonal fasciole rather indistinct; operculum solid, black, rather short, 

 concave, its outline like that of a half-shut fan. Height of shell, 75; 

 maximum diameter, 50 ; length of aperture, 47 mm. Another specimen is 

 90 mm. in total length. 



