30 TRACHELIPODA. COLOMBELLA. 
most part covered with a thin, fuscuous, membranous epi- 
dermis; spire short, terminating in a papillary apex ; aper- 
ture oblong ; columella plicated, the lower plaits being the 
largest ; base emarginate ; destitute of an operculum. 
Voluta lyra. Pilate III. fig. 32. 
The variety of forms comprehended in this genus, render it necessary to 
constitute five subdivisions for their reception, — viz. 
SUBDIVISION I. — Papilla large and smooth. 
Section 1. — Coronated. 
Section 2.— Not coronated. 
SUBDIVISION II. —Vespertiliones ; papilla tuberculated. 
SUBDIVISION III.— Papilla smooth, medium sized, and subacute. 
Section 1. —Ventricosiones, or bellied species. 
Section 2.— Graciliones, or slender species. 
Section 3. — Musicales, or Music Volutes. 
SUBDIVISION IV.— Mammillares. Mammillary species, with a 
mammiform apex. 
SUB-DIVISION V.—Mitrijormes. Mitre-shaped. 
The volute, in a recent state, inhabit the seas of warm climates. They are 
met with, in a fossil state, in the formations above the chalk, in the Calcaire 
grossier of Grignon and Laugnan, the London Clay and Crag; and the 
Voluta Lyra has been found in the Cornbrash under the Chalk. 
Genus X.— MITRA. — Lamarck. 
Generic Character. — Shell subcylindrical, elongated> 
generally covered with a thin horny epidermis; spire vari- 
able in length, but generally greater than the extent of the 
aperture; aperture longitudinal, elongated, notched at the 
base, and terminating in a very short canal ; columella pro- 
vided with a series of plaits, which are sharp at the edge, 
and the lower ones smallest; margin of outer lip usually 
sharp, in other species it is somewhat thickened, and crenu- 
lated, and even provided with an obtuse tooth at the upper 
part interiorly. 
Mitra plicatula. Plate III. fig. 40. Mitra Dufrensi. 
Plate III. fig. 31. Both from the Paris basin. 
The Mitre inhabit the tropical seas; most of them in the Indian Ocean. 
They are found fossil in almost all the Tertiary formations. 
The species are liable to considerable variations in external form; we give 
representations of the most conspicuous of these. 
Genus XI.— COLOMBELLA. — Lamarck, 
Generic Character.— Shell oblong-ovate, invested with 
a thin epidermis; spire short; aperture elongated, con- 
tracted and narrow, usually about half the length of the 
