THE SHELL-FISH OF THE COAST. 17 
tract immediate attention is the pear-conch, which 
is about the largest shell of the coast,—indeed, one 
of the largest shells of the entire North American 
coast. Not uncommonly the animal is found within 
the shell, where, it will be observed, it has closely 
withdrawn itself, partially closing up the aperture 
by means of a horny disk attached to its foot, known 
as the ‘operculum.’ Thus shut up in its house the 
animal is fairly secure from its enemies, and, if suf- 
ficiently fortunate to regain the incoming waters, 
may again rejoice in its favorite haunts. But too 
long exposure to the dry 
atmosphere will prove 
fatal to it, as it like- 
wise would to the greater 
number of marine snails. 
The pear-conch, of 
which we recognize two 
species, one furnished 
with tubercles on the an- 
gles of its whorls (Pulgur 
carica), and the other 
practically devoid of tu- 
bercles, and showing a ca- 
nalicule running around 
the tops of the whorls (7. 
canaliculatus), inhabits the 
tidal zone, where it buries 
itself to the depth of a few 
inches in the sand. Its ah cS tee al 
presence can frequently be detected by hollows in 
the sand, into which it has introduced itself by bur- 
5 Me 
