XV1ll INTRODUCTION. 
siderable rapidity ; whilst the marine Turtles have them 
modified into true paddles, the toes being entirely conceal- 
ed by hard scaled skin. ‘These modifications of form are 
very interesting, as evincing an admirable adaptation of a 
general plan of structure to the varied habits of the dif- 
ferent groups. 
The jaws of all these different forms are covered with a 
hard, sharp, horny beak, the lower portion of which shuts 
within the upper, and the portions of food are cut or 
snapped off, as it were, on the principle of shears. The 
aquatic species aid the separation of their food, which they 
seize with their jaws, by tearing it by means of their long 
and sharp claws. They thus pursue, seize, and tear in 
pieces living frogs, and other aquatic reptiles, fish, and even 
young water birds; and so forcible and violent is their 
bite, that I have known a stick of half an inch in diameter 
at once snapped asunder by the Jaws of a snapping Turtle, 
Chelydra serpentina; and a specimen of T'rionya, lately in 
the possession of Mr. Cross, of the Surrey Zoological Gar- 
dens, snapped off the finger of a sailor when on his voyage 
to this country. 
The whole of the Testudinata are strictly oviparous, and 
the egg is covered by a calcareous shell, like that of birds ; 
the eggs of the land Tortoises, as well as those of the 
marine Turtles, are generally round; but those of the 
fresh-water genera are usually more or less oval or ellip~ 
tical. The multitudes of fresh-water Tortoises in some 
districts is astonishingly great, and their eggs form a 
lucrative article of commerce from the quantity of oil which 
is obtained from them. 
It has been already stated that we have no indigenous 
species of this order. There are, however, on record seve- 
ral well-authenticated instances of marine Turtles, of two 
