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420 THE OCEAN WORLD. 
children—those charming ignoramuses—who have been taught to 
repeat the well-known couplet— 
“ Snail, snail, come out of your hole, 
Or else I’ll beat you black as a coal,” 
which finds its counterpart in all European languages, There are 
two pairs of these tentacles or horns ; one pair quite in front and 
above, and another smaller and less forward. The first, or upper 
pair, is distinguished by its size, and also by a black spot or point at 
their ‘extremity, which are said to be the eye-specks of the snail. 
These tentacles differ in many respects from the same organs in 
other molluscs; they are retractile, and can be drawn altogether 
within the animal into a sort of sheath, by the contraction of the 
muscles. 
At the anterior extremity of the head we find a sort of plaited 
opening, which is the mouth ; it is of moderate extent, closed in front 
by two lips, and armed with two shear-like organs of horny con- 
sistence, one of them being a sort of rasp, which occupies the place 
of the buccal cavity, and may be called a tongue; the other is a 
median jaw, placed transversely in the membranous walls of the 
palate, terminating in a free edge, armed with small teeth. This 
cutting blade, however, executes no movement; but the lingual 
organ, pressing all alimentary matter forcibly against its lower edge, 
effects their mastication, and enables it to dispose of fruit, tender 
leaves, mushrooms, and other substances easily divided. 
At the bottom of the mouth is an cesophagus, or gullet, to which 
succeeds a stomach of moderate size. The intestine lies in folds 
round the liver, which is divided into four lobes, and terminates in a 
special orifice. 
The little lung of the snail is placed in a cavity, vast for its size, 
just above the general mass of the viscera, and occupies all the last 
spiral turn of the cavity. 
The mechanism of respiration is as follows: The animal inhales 
the air into its lung by forcibly dilating the pulmonary orifice, which 
lies in the largest spiral turn of the shell. In order to expel the air 
respired by the lung, it withdraws its body into the narrower part of 
the shell, where it gathers itself up completely, even to its head and 
feet, and by this compression of all its little being it expels the air 
which fills it. These respiratory movements, however, are not 
regular, but succeed each other only at certain intervals. Life would 
be too hard for the poor snail were it passed in such violent efforts 
as would be necessary if it respired as the larger animals do. In its 
