Epitoniun/.] GASTROPODA. 319 



cated in front, extending far in advance of the head. Jaws oval or 

 semicircular, spiny, or denticulated only on the margin ; radula 

 composed of elongated unciform or aciculated teeth, many in a series. 

 Sexes distinct. 



Shell usually white and polished, turriculated, perforate, but the 

 umbilicus frequently covered by an expansion of the inner lip ; whorls 

 numerous, convex, usually loosely coiled, often barely or not at all in 

 contact ; aperture entire, circular or oval. Operculum corneous, few- 

 whorled, nucleus nearly central. 



The animals of this family are predaceous, and living in all seas ; 

 they are somewhat closely allied to the JfottJiintr, of which they may 

 be regarded as creeping representatives. The shells, remotely sug- 

 gesting Turritella, are remarkable for the extreme elegance of their 

 form and delicacy of sculpture. 



KEY TO GENERA. 



A. Shell turbinate, aperture channelled in front, umbilicate, 



umbilicus surrounded and restricted by a callus . . . . CROSSEA. 



B. Shell turreted, many-whorled. 



. Whorls longitudinally ribbed or lamellate ; peristome con- 

 tinuous, thickened, and reflected ; umbilicate or im- 

 perforate . . . . . . . . . . EPITONTUM. 



aa. Whorls smooth or with spiral riblets, peristome discon- 

 tinuous, lip thin and simple ; perforate . . . . ACLIS. 



Genus 1. EPITONIUM, Bolten, 1798. 



Epitonium, Bolten, Mus. Bolten. (2), 1798,91. Type: Turbo scalaris, L. 

 Scala (Humphrey) of authors. Cyclostotna, Lamarck, 1799. Scalaria, 

 Lamarck, 1801. Scalatarius, Diimeril, 1806. Ac-iona, Leach, 1815. 



Animal having a short head ; tentacles subulate ; foot lanceolate 

 behind, truncated in front, with an anterior marginal groove ; sole 

 with a posterior longitudinal groove ; gill simple, pectinated ; intro- 

 mittant organ large, curved, and pointed ; mantle forming a rudi- 

 mentary siphonal fold at the anterior part of the branchial chamber. 



Shell usually white and polished, turriculated, perforate, but the 

 umbilicus frequently covered by an expansion of the inner lip ; spire 

 elongated, the apex more or less inflected ; whorls numerous, rounded, 

 in contact or separated, ornamented with longitudinal ribs or thin 

 lamellae, often continuous across the suture ; peristome entire, 

 thickened, reflected. 



The genus commenced in the Trias, and has continued its develop- 

 ment to the present time ; about 200 fossil species have been described, 

 and not far from the same number Recent. They are found from low 

 water to 80, 100, or 400 fathoms, and occur throughout the world, 

 the Arctic seas furnishing representations of peculiar type ; but the 

 largest, finest, and most typical species are tropical. The West Indian 

 province appears to be the metropolis of the genus. 



Vernacular Name. Wentle-trap shell. 



