333 



HISTORY OF FISHES. 



rather from their habits than their con forma- 

 tion: and, upon examination, there will be 

 less variety found between them than between 

 birds that live upon land, and those that swim 

 upon the water. 



Yet, though nature seems to have made 

 but few distinctions among these animals, as 

 to their conformation, yet, in their habits, they 

 are very dissimilar ; as these result from dif- 

 ferent qualities of their food, and the different 

 sorts of enemies they have to avoid or encoun- 

 ter. I will therefore exhibit their figure and 

 conformation under one common description, 

 by which their slight differences will be more 

 obvious ; and then I will give a separate his- 

 tory of the manners of each, as naturalists and 

 travellers have taught us. 



All tortoises, in their external form, pretty 

 much resemble each other ; their outward 

 covering being composed of two great shells, 

 the one laid upon the other, and only touch- 

 ing at the edges: however, when we come to 

 look closer we shall find that the upper shell 

 is composed of no less than thirteen pieces, 

 which are laid flat upon the ribs, like the tiles 

 of a house, by which the shell is kept arched 

 and supported. The shells both above and 

 below that, which seem, to an inattentive ob- 

 server, to make each but one piece, are bound 

 together at the edges by very strong and hard 

 ligaments, yet with some small share of mo- 

 tion. There are two holes at either edge of 

 this vaulted body ; one for a very small head, 

 shoulders, and arms, to peep through ; the other 

 at the opposite edge, for the feet and the tail. 

 These shells the animal is never disengaged 

 from : and they serve for its defence against 

 every creature but man. 1 



The tortoise has but a small head, with no 

 teeth ; having only two bony ridges in the 

 place, serrated and hard. These serve to 



gather and grind its food; and such is the 

 amazing strength of the jaws, that it is im- 

 possible to open them where they once have 

 fastened. Even when the head is cut off, the 

 jaws still keep their hold ; and the muscles in 

 death, preserve a tenacious rigidity. Indeed, 

 the animal is possessed of equal strength in 



1 There are various species of land tortoise, such as 

 the Indian tortoise the Radiated tortoise the Tabular 

 tortoise the Geometrical tortoise the Starred tortoise 



the Leopard tortoise the Kinyxis tortoise, &c. and 



the Emys tortoise, which latter term is employed to 

 designate the species that live habitually in fresh water. 



all other parts of its body : the legs, though 

 short, are inconceivably strong; and torpid as 

 the tortoise may appear, it has been known 

 to carry five men standing upon its back, with 

 apparent ease and unconcern. Its manner of 

 going forward is by moving its legs one after 

 the other ; and the claws with which the toes 

 are furnished, sink into the ground like the 

 nails of an iron-shod wheel, and thus assist 

 its progression. 



With respect to its internal parts, not to 

 enter into minute anatomical disquisitions, it 

 may not be improper to observe, that the 

 blood circulates in this animal as in some 

 cartilaginous fishes, and something in the 

 manner of a child in the womb. The great- 

 est quantity of the blood passes directly from 

 the vena cava into the left ventricle of the 

 heart, which communicates with the right 

 ventricle by an opening ; while the auricles 

 only receive what the ventricles seem incap- 

 able of admitting. Thus the blood is driven 

 by a very short passage through the circula- 

 tion ; and the lungs seem to lend only 

 occasional assistance. From this conforma- 

 tion, the animal can subsist for some time, 

 without using the lungs, or breathing; at 

 least the lungs are not so necessary an instru- 

 ment for driving on the circulation as with us. 



Such is the general structure of this animal, 

 whether found to live by land or water. 

 With regard to the differences of these ani- 

 mals, the land-tortoise, from its habits of 

 making use of its feet in walking, is much 

 more nimble upon land than the sea-turtle : 

 the land-tortoise, if thrown upon its back, by 

 rocking and balancing its body, like a child 

 rocking in a cradle, at last turns itself upon 

 its face again ; but the turtle, when once 

 turned, continues without being able to move 

 from the spot. In comparing the feet also of 

 these animals, the nails upon the toes of one 

 that has long been used to scratch for subsis- 

 tence upon land, are blunt and worn ; while 

 those that have only been employed in swim- 

 ming, are sharp and long, and have more the 

 similitude of fins. The brain of the land- 

 tortoise is but small ; and yet it is three times 

 as large as that of the turtle. There is a differ- 

 ence also in the shape of their eggs, and in the 

 passage by which they are excluded ; for, in 

 the land-tortoise, the passage is so narrow, 

 that the egg conforms to the shape of the 

 aperture, and though round when in the body, 

 yet becomes much more oblong than those of 

 fowls upon being excluded; otherwise they 

 would never be able to pass through the bony 

 canal by which they are protruded ; on the 

 contrary, the passage is wider in the turtle, 

 and therefore its eggs are round. These are 

 the most striking distinctions ; but that which 

 is most known is their size ; the land-tortoise 



