MONOPTYGMA. TRACHELIPODA. Bi 
TRIBE III.—PLICACEA. 
Shells with the aperture somewhat contracted, and the 
columella plaited. 
Genus LVIII. — PYRAMIDELLA. — Lamarck. 
Generic Character. — Shell turreted, smooth, polished, 
destitute of epidermis; body small; spire long, consisting 
of numerous volutions, terminating in an acute apex; 
aperture smal], somewhat modified by the base of the body; 
a little oblong, and posteriorly rounded ; outer lip sharp, 
slightly expanded, turned upwards at the base, and united 
to the columella; columella tortuous, and provided with 
several transverse plaits. 
Pyramidella terebellata, Plate V. fig. 26. 
The Pyramidelle are very limited in number, and are marine shells, chiefly 
inhabiting the warmer portions of the globe. 
Fossil species are rare, and met with only in the Cretaceous group of rocks. 
Genus LIX.— TORNATELLA. — Lamarck. 
Generic Character.— Shell subcylindrical, oval or oblong; 
usually transversely striated, and destitute of an epidermis ; 
spire generally very short, and somewhat obtuse, in a few 
species a little elongated, and subacute ; aperture longitu- 
dinal and elongated, occupying about two-thirds the length 
of the shell, contracted and acute above, widened and 
rounded below, outer lip plain, sharp on the edge, and 
a little thickened in the centre ; inner lip thin, slightly re- 
flected on the columella, which is thickened, spiral, and 
provided with one or two plaits near its base. 
Tornatella cuspidatus, Plate IV. fig. 23. Found in the 
Oolite at Ancliffe, 
The Tornatelle are distinguished from the Volvarie, by the former being 
destitute of a notch at the base of the aperture ; and its short spire, striated or 
grooved external surface, and its considerably lengthened aperture, are cha- 
racters which remove it from the Pyramidelle. 
This genus is rather limited in species; they inhabit the Indian Ocean, 
European seas, and one is found on the British coasts. 
Fossil Tornatelle occur in the Calcaire-grossiér at Bordeaux and Paris; 
and they are met with in England in the Crag, London Clay, and Inferior 
Oolite. 
Genus LX.— MONOPTYGMA. — Lea. 
Generic Character. — Shell elongated; spire conical, 
tapering to an acute apex; aperture long, narrow, terminating 
