CLAUSILIA. 
177 
Shell about a quarter of an inch long, slender, and 
tapering to a rather sharp point, transparent yellowish 
horn-colour, slightly striate longitudinally ; spire 
consisting of from six to nine raised and well-defined 
volutions ; aperture roundish-oval ; the peristome 
thin, simple, and a little reflected at the pillar, so as 
to form a slight umbilicus. In old and full-grown 
shells there may be observed a slight fold or tooth 
about the middle of the pillar, but which is seldom 
to be met with. 
These shells vary considerably in their size, colour, 
and shape, some being more ventricose than others. 
Mr. Jeffreys, probably forgetting that these animals 
are all hermaphrodite, observes, The females have 
their shells much more ventricose and with fewer 
volutions.” {Linn. Trans, xvi. 351.) 
13. Clausilia. (Close Shell.) 
The animal like Bulimus ; but the shell is reversed, 
with an elongated, slender, fusiform spire, the 
last volution less tumid than the one before it, 
with an obtuse or papillary summit; aperture 
oval, oblique, united all round and margined, 
toothed ; throat furnished with an internal spi- 
ral shelly plait, or clausium^ fixed on an elastic 
pedicle, which closes the cavity when the animal 
is withdrawn. 
Jaw lunate, narrow, with a slight central pro- 
minence, nearly smooth. 
The elegant spindle-shaped outline of the shell of 
this family having the last volution slenderer than the 
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