"uagB. 11 "] PROCEEDINGS OF THE NATIONAL MUSEUM. 321 



Genus CHRYSODOMUS Swainson. 



Chrysodomus amiautus sp. nov. 



Plate V, Fig. 10. 



Shell large, thin, white, with six whorls and a small bat prominent 

 inflated subglobular nucleus; spiral sculpture of numerous close-sel 

 rounded narrow ridges, of which part are larger than the others ; ou 

 the early whorls two or three of the primaries are conspicuous on the 

 periphery, with one or two finer ones intercalated; later the peripheral 

 spirals merge with the other primaries, as to size and prominence, and 

 on the last whorl there are four or five intercalary threads between 

 the primaries, the space between the latter, from center to center, 

 averaging 2.5 mm to each set; transverse sculpture shows only in fine, 

 slightly irregular lines of growth ; the whorls from and including the 

 third are inflated, and the suture, though not channeled, is strongly 

 marked; the canal is short and recurved, the si phonal fasciole indis- 

 tinct; the aperture is wide, the outer lip, prominent in the middle, re- 

 ceding toward the suture and the canal, smooth not thickened, whitish 

 internally; inner lip concave, with a thin glaze of polished callus, 

 slightly brown tinted; pillar twisted and the axis minutely pervious; 

 the aperture longer than half the shell; operculum brown, moderately 

 stout, apically pointed; maximum longitude of shell, 76; maximum 

 latitude, 43; longitude of aperture, 45 mm . 



Hab.— Station 2839, near the Santa Barbara Islands, off the coast of 

 California, in 414 fathoms, sand; bottom temperature not taken. 



This fine species does not require any comparisons to indicate its 

 distinctness from forms already known. Several specimens of different 

 ages were obtained, all the adults showing more or less strongly the 

 effect of carbonic acid or other eroding agency on the upper whorls, 

 though living when obtained. 



The soft parts are whitish externally. The foot double-edged in 

 front, but not auriculate, the tail-end gently rounded; the tentacles, 

 as contracted in alcohol, are subtriangular and somewhat flattened ; 

 there is no pigmented organ of vision nor any distinct vestige of such 

 an organ without pigment. The gills and osphradium are as usual; 

 also the female muciparous gland, which furnishes the material for the 

 ovicapsules; the vent projects slightly, but is not free; the penis is 

 not remarkably large, but is geniculate as usual, its front edge thick 

 and rounded, its hinder edge sharp and transversely wrinkled, slightly 

 projecting distally behind a stout, short, conical papilla. The male, as 

 usual, is smaller than the females. The dentition resembles that of 

 Chrysodomus despectus, as figured by Friele (Moll. Norske Nordh. Exp., 

 I, PI. iv, Fig. 9), or even more that of C. latericeus (op. cif., PL Vi, Fig. 16), 

 from which it differs by the outer denticle of the laterals being propor- 

 tionately a little longer, and the three denticles of the rhachidian being 

 Proc. N. M. 89—21 



