TRICHOTROPIDyE. ' 41 



tudinal lamellae; aperture oval, slightly produced in front, inner 

 lip smooth, rounded, slightly reflexed in front, outer lip simple, 

 acute. T. GOULDII, A. Acl., W. Coast Central Am. 



Subgenus GYROTROPSIS, Gabb, 1876. 



Shell thin, spire elevated, umbilicus wide, funnel-shaped, last 

 whorl an gul sited above and below the periphery, and covered 

 with very thin foliated longitudinal varices. T. SQUAMOSA, Gabb. 

 Cretaceous, N. Carolina (PI. 7, fig. 39). 



? Genus SEPARATISTA, Gray, 1847. 



Shell subdiscoidal, with very short spire, the last whorl sepa- 

 rated from its predecessors, forming a very large umbilicus ; 

 aperture slightly channeled at the base. This group, which I 

 formerly included in Muricidae (see Manual, ii, p. 213), is doubt- 

 fully referred to Trichotropidffi by Dr. Fischer and others. 



Genus TORELLIA, Loven, in Jeffreys, 1867. 



Shell narrowly perforated, globular, covered by a pilose epi- 

 dermis ; spire short, depressed; mouth rounded, with a hardly 

 perceptible basal sinus; lip thin, curved; columella concave, 

 subtruncated at the base. 



Differs from Trichotropis in being holostomate and subglobose. 



Trachyoma, Seguenza, is a S3'nonym. T. VESTJTA. Jeffreys. 

 Arctic Seas. 



Genus SEGUENZIA, Jeffreys, 1876. 



Shell thin, turbinate or subtrochoid, translucent, the outer 

 layer very slight, somewhat nacreous in fresh specimens, with 

 spiral carinations ; aperture irregular, sinuous 'behind, columella 

 twisted, base with a sinus. Operculum thin, oval, with sub- 

 central nucleus, and with obsolete, numerous concentric lines 

 (PL 7, fig. 4L). Radula (PI. 7, fig. 40). 



The position of this group of deep-sea minute shells is not well 

 ascertained. The soft parts have not been described. Verrill, 

 who obtained the dentition, formed for the species a family, which 

 he located near Chenopus ; Dr. Jeffreys places them near Solar- 

 iidte and Dr. Watson in Trochidre (on account of the operculum 

 and slight pearly layer of the shell). I place the group here, for 

 the present. 



