TRICHOTROPID^. 223 



Distr. — 2 sp. Red Sea, Atlantic, Mazatlan. R. Bollandiana, 

 Petit (Ixvii, 50). 



Shell paliidiniform, thin, with a brown epidermis; whorls 

 ventricose ; aperture ovate-oblique, slightly effused at the base, 

 margins disunited ; inner lip oblique, rather sinuated in the 

 middle ; outer lip acute, entire. No operculum. 



Animal pelagic, resembling lanthina, and like it provided with 

 a vesicular float. 



ScALiTES, Conrad. 



Distr. — Silurian; United States. S. angulatus^Conr. (Ixvii, 51). 



Shell turriculated, whorls flattened above, angulated at the 

 shoulder, and convex below ; outer lip sinuous ; umbilicus none, 

 or verj^ small. 



RAPHTSTOMA, Hall. Shell turbinated, depressed, flattened and 

 angulated above, convex below ; aperture subtrigonal, columellar 

 lip excavated in the middle and produced to the right below. S. 

 staminea^ Hall (Ixvii, 52). 



HOLOPEA, Hall. ( Cyclora, Hall.) Is a palaeozoic group com- 

 posed of incongruous elements. Its first species has been 

 referred to Littorinidae, another evidently belongs to Naticidag, 

 a third resembles lanthina. The species are mostly casts. 

 There appears to be no good reason for retaining the group. 



Family TRICHOTROPIDJE. 



Shell thin, turbinated, carinated, the ridges with epidermal 

 fringes, in fresh or living specimens ; columella obliquely trun- 

 cated. Operculum lamellar, nucleus external. 



Animal with a short, broad head ; tentacles distant, with eyes 

 on the middle ; proboscis long, retractile. Dentition, central 

 teeth single, hamate, denticulated ; uncini three on each side, of 

 which the inner is denticulate, the others simple. 



Truchotrgpis, Brod. 



Etym. — Thrix (trichos), hair, and tropis^ keel. 



Syn. — Verena, Gray. Tropiphora, Loven. Ariadna, Fischer. 

 Trichophore, Desh. 



Distr. — 15 sp. Circumboreal. T. borealis, Gould (Ixvii, 53). 

 Fossil. Cret. — . 



Characters those of the familj^ 



IPHINOE, H. and A. Adams. Shell widely umbilicate, aperture 

 subtriangular. T. unicarinatus, Sowb. (Ixvii, 54 \ 



ALORA, H. Adams. Shell ovate-fusiform, slightly umbilicated, 

 thin; spire elevated; whorls convex, cancellated with elevated 

 spiral ribs and thin lamellae ; aperture oval, slightly produced 

 in front ; inner lip smooth, rounded, slightly reflexed at the fore- 

 part ; outer lip simple, acute. T. Gouldii, A.' Ad. W. Coast 

 Central Am. 



