XX 
INTRODUCTION. 
in no instance to allow of the retraction of the head and limbs,—and the feet 
are modified into perfect fin-like oars; the toes being flat and far asunder, and 
the whole of them enveloped in a continuous and undivided skin. These ani¬ 
mals are all marine, and generally vegetable feeders. One species, constituting 
the genus Sphargis , is covered with a leathery skin, instead of the horny plates 
which form the usual protection of the osseous shell. 
Such is a brief, but necessary sketch of those characters of the principal 
groups or families of the Testudinata, which appear to determine their habits 
and modes of life. It will be obvious that so meagre a sketch can only be 
intended to render intelligible, the account of their natural history which 
follows. 
Whilst we see, in the other classes of the Vertebrata, the functions and enjoy¬ 
ments of life provided for by the attributes of strength, of fleetness, or of acute 
powers of sensation; or, where these are wanting, by such a peculiar develop¬ 
ment of the mental faculties, as shall equally avail their possessor in the fulfill¬ 
ment of those destinies which appertain to him in the situation which he holds 
in the scale of being; we turn, with a feeling of disappointment, to the slug¬ 
gish, torpid habits, and rude, ungainly structure which characterize most of the 
Testudinata. But although these animals have not the power of escaping 
from danger by swiftness of foot, they are provided, instead of such a means 
of safety, with a hard solid case, impervious to the teeth even of beasts of prey; 
a shelter more secure than the burrow of the marmot or the mole. Although 
they cannot, like the migratory birds, wander from place to place, on the ap¬ 
proach of winter, in search of a more genial climate, yet their peculiar confor¬ 
mation renders such a change unnecessary, by producing a greater or less 
degree of torpor and insensibility as the cold advances, until every faculty and 
function of life becomes extinct, and sensation itself is rendered less and less 
capable of suffering, exactly in proportion as the cause of pain and distress, in 
the higher grades of animal life, increases. It is not only in those animals 
whose habits are most obviously interesting, that we are to look for illustra¬ 
tions of the wisdom and power of the Creator, and of the universal adaptation 
of the structure of animals to their habits: in this respect the tortoise and the 
