XXI] 
INTRODUCTION. 
This is repeated with greater or less rapidity, until a considerable portion has 
been taken, and the food is at once swallowed without any attempt at masti¬ 
cation. As the oesophagus is large, and very distensible, large pieces of the 
stalk are often swallowed whole, without inconvenience. A specimen of 
T areolata , which I kept some years since, and which was so tame as to eat 
readily from my hand, would swallow in this way a piece of the stalk of cab¬ 
bage, or a small piece of hard pear, nearly as long as its body, without biting 
it sufficiently to separate it into smaller pieces, or even to render it flexible; 
so that the posterior part of the stomach must have been forced backwards by 
it almost to the extent of the abdominal cavity, and this without producing 
the slightest apparent disturbance to the animal. 
From these exclusively vegetable feeders we pass towards the fresh-water 
tortoises, which live on animal substances only, by the intermediate form of 
the Box Tortoises, which live on food of a mixed kind; of these, the common 
American species Terrapene clausa devours not only various vegetable matters, 
but snails, worms, and other small animals. The European species of the 
same genus, T europcea , approaches more nearly in form and habit to the 
fresh-water tortoises, and may in fact be considered as the common fresh¬ 
water tortoise of Europe. Its common food consists of fish and other aquatic 
animals; and as it always leaves the air-bag of the fish which it eats, the num* 
her of these which float on the surface of a lake or pond is considered as an 
indication of the comparative number of tortoises which inhabit it. Yet even 
this species, so carnivorous in its general habits, is not necessarily confined to 
animal food ; for we are told that in some parts of Europe, where it is eaten 
by the inhabitants, it is not only fed but fattened upon grains. 
Such, however, is far from being the case with the more typical fresh-water 
species, including the remainder of the family Emydidce , and the whole of the 
Chelydidce and Trionychidce. These live exclusively on animal food of differ-^ 
ent kinds, such as fish, batrachian animals, the young of water birds, aquatic 
mollusca and insects. They are generally furnished with long sharp claws, by 
which they tear their prey to pieces. These are particularly long in some of 
the American species, as Emys irrigata , ornata , decussata , in which they not 
unfrequently attain an inch or more in length. When the Emydes seize their 
