152 
HELICID-®. 
composed of six or seven raised volutions, slightly 
striate longitudinally ; aperture oblong-oval, with 
the margin white and reflected, forming a slight um- 
bilicus behind the pillar. The young shell conical, 
pyramidal, with a subquadrangular mouth. 
It scarcely differs, except in size, from the last 
species ; but it is of a paler brown, with the volu- 
tions more rounded, and the peristome is white. 
Varies like the last, and being more common, the 
varieties are more often observed. 
The jaw of B, montanus and B, ohscurus is lunate, 
rather narrow, crenated on the edge. 
The Rev. Mr. Sheppard remarks, These shells, 
particularly in their young state, show great sagacity 
and ingenuity, by covering themselves with a coat 
adapted to the different situations in which they are 
found ; and when so covered, it is almost impossible 
for any other than a conchological eye to discover 
them. If its abode be upon the trunk of a tree 
covered with lichen, then is the epidermis so con- 
structed as to cause the shell to resemble a little knot 
on the bark covered with such substance. If on a 
smooth tree, from whose bark issue small sessile buds, 
as is frequently the case, it will pass off very well 
for one of them ; and on a dry bank, or the lower 
part of the body of a tree splashed with mud, its 
appearance will be that of a misshapen pointed piece 
of dirt.” {Linn. Trans, xvi. 166.) 
b. Shell turreted, white, handed, covered with a thin 
periostracum ; whorls rapidly and regularly en- 
larging ; mouth small; peristome thin, scarcely 
