282 BULLETIN OF THE 



versely ribbed, but, in general, there is no sculpture or but little; peristome 

 slightly reflexed, rounded in front, simple, sharp, not continuous over the 

 body. Surface brilliantly polished and apparently without epidermis. 



This group is instituted to contain a few species which I cannot find any 

 place for in existing groups. The soft parts are unfortunately unknown. If 

 Verrill's Cingula apicina should belong here, as seems possible, the animal 

 would be blind and the operculum paucispiral ; but the nucleus of that species 

 is styliform while in all ours it is trochiform, and I do not feel confident that 

 they belong together. There are several of the deep-water Rissom which have 

 a small brown trochiform nucleus, somewhat like the present group ; but there 

 is little which cari be depended upon in the general character of the larval 

 shell to determine generic or even specific affinities, in' the absence of other 

 confirmatory evidence, as a student soon finds out who examines into the mat- 

 ter thoroughly. But neither in Aclis, nor in any of the Eulirnidce, have I so 

 far discovered any such discrepancy between the material and color of the nu- 

 cleus and the rest of the shell as is here presented. All the species are very 

 thin. 



Benthonella gaza n. s. 



Shell elongated, glistening opaque white, extremely thin, with two and a 

 half larval and five later whorls. Nucleus trochiform, brown, polished, with a 

 single carina above the periphery; other whorls full, rounded, the earlier ones 

 marked with a few faint flexuous transverse waves, the rest with only lines of 

 growth. The whorls are full and rounded, the .suture distinct; base full, 

 rounded, with a small umbilicus, in front of which is reflected the thin inner 

 lip; aperture rounded, lip slightly reflected, not thickened. Lon. of shell, 6.5; 

 of last whorl, 3.6; max. lat. of shell, 3.5 mm. 



Habitat. Station 2352, west of Cuba, in 463 fms., coral, U. S. Fish Com- 

 mission. 



This species may be regarded as the type. Its polished white rounded 

 simple whorls and brown tip present an elegant appearance. 



Benthonella Fischeri n. s. 



Shell resembling the last, but shorter and more trochiform and with a smaller 

 umbilicus. Nucleus of three brown polished whorls, rather flattened on the 

 apex, and smooth or with two faint carina?, the lower one against the suture, 

 the other behind the periphery ; subsequent whorls four or five, rapidly enlar- 

 ging, smooth, polished, inflated, with a few small transverse waves behind the 

 suture in some specimens ; in the early whorls these waves do not extend back 

 from the suture more than half the width of the whorl, and in other specimens 

 are absent; incremental lines which do not affect the polish of the surface are 

 the only other sculpture; base full and rounded; umbilicus minute, partly 

 but not wholly covered by the reflected inner lip ; peristome thin, sharp, broken 



