dall: mollusca and brachiopoda. 297 



convex ; axial scul[)ture of numerous (on the penultimate whorl about twenty) low 

 rounded ribs, with shallow, subcqual interspaces, strongest at the angle, obsolete 

 on the tabulation and on the last whorl, extending on the spire to the succeeding 

 suture; tlie incremental lines are also rather conspicuous ; spiral sculpture in front 

 of the angle of (on tlic spire about four, on the last whorl about twenty) low 

 rounded subequal spiral threads with wider interspaces, a little turgid where they 

 cross tlie ribs, especially on the spire, and more crowded on tlic last whorl, anteriorly, 

 where tliey extend to tiic brink of the umbilicus; aperture subtriangular, the outer 

 lip thin, not reflected ; body witli a tliiu wash of callus ; pillar thin, straight, with 

 Miree plications, the middle one strongest ; canal obsolete or none ; umbilicus rather 

 large, funicular, its walls vertically striate, the opening partly concealed by the pil- 

 lar lip; in the young the umbilicus is relatively much smaller; operculum absent. 

 Length of shell, 16; of last whorl, 11 ; of aperture, 8; max. diam. 8.3 mm. Length 

 of figured specimen, 10 mm. 



U. S. S. " Albatross," station 2980, in 603 fathoms, mud, bottom temperature 

 39° F. U. S. N. Mus. 110,026. Also at stations 3316, 3194, 2839, 2923, 2936, 

 and 4339, from off Tillamook Bay, Oregon, south to the vicinity of San Diego, 

 California, in from 92 to 786 fathoms, temperatures from 37°. 3 to 49° F. 



The specimen figured, from 2936, is about two-thirds grown; the others were 

 discovered later. It does not show the third feeble plait, nor the somewhat sud- 

 den enlargement of the last whorl, both noticeable in the fully adult shell. It ha.s 

 the aspect of an Admete, in spite of the presence of an umbilicus, but is perhaps 

 only a delicate form of Trigonostoma. 



Vohiiidae. 



CAUICELLINAE. 



ADELOITIELON Dall. 



Adelomehn Dall, Nautilus, April, 190G, 19, p. 14.S; type Valuta ancilla Solander ; 

 Smithsonian Misc. Coll. Quarterly, 1907, 48, p. 365. 



In making a thorough and too long delayed examination of the systematic his- 

 tory of the Volntidae, in connection with a revision I have been making of the 

 group, I discovered that the type of the genus Scaphella (under which I had 

 formerly included the dull-colored American group of Volutes) is F. undulata, 

 which belongs to the group of which Amoria Gray is a synonymic name ; and the 

 type of Cymbiola Swainson, which has been used for them by several authors, is 

 Voluta vesprrtilio Linne. Both of those forms have a shelly protoconch, and be- 

 long to another sul)fainily. Scaphella has a peculiar brilliant surface enamel 

 which no American Volute possesses, and a totally dilTorcnt radular dentition. It 

 is obvious, therefore, that neither of these groups can properly cont^niu the Ameri- 

 can shells whicli form an extremely natural group, and to which I have given the 

 name of Adelomelon. 



