TRICHOTROPID^. 41 



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

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

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



Subgenus GYROTROPSTS, Gabb, 1876. 



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

 whorl angulated 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 Muricidse (see Manual, ii, p. 213), is doubt- 

 fully referred to Trichotropidse 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 synonym. T. VESTITA, 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 

 (PI. 7, fig. 41). 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. Yerrill, 

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

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

 iidae and Dr. Watson in Trochidse (on account of the operculum 

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

 the present. 



