THE LIVING WORLD. 
213 
eval waters, and what analogy exists between species of our time and the 
monster saurians and ophidians whose fossil remains, or traditionary lore, 
enable us to form a just conception of their size and habits. It must not be 
supposed that the turtles, with which we are so familiar, had any less dis¬ 
tinguished progenitors than the ravenous crocodile, however great may be the 
dissimilarity of disposition between the two species. The persistent search of 
palaeontologists has brought to light many strange things during the past two 
centuries, by whose discoveries it has been shown that the world was one time 
peopled by colossal amphibians and mammals whose appearance, in life, would 
serve to inspire the greatest dread in all mankind even in this day, with all 
the engines of destruction at our command. 
The ancients affirmed that there were turtles whose shells were so large 
as to serve for the covering of a house, a statement which was regarded as 
highly exaggerative until remains of the gigantic glyptodon (carved tooth) and 
protostega were uncovered and subjected to examination, when it was found 
that these creatures were the equals in size of any amphibian that roamed the 
sea, and with a mouth large enough, as Sir John Hunter states, to admit a 
horse and cart. The shell of such an animal might easily suffice to cover a 
house of considerable size, and but for its sluggish movements might have 
been a most formidable creature. So strong was its armament that a ball from 
any modern firearm, short of a cannon, could produce no effect upon it. 
CHARACTERISTICS OF THE TORTOISE. 
The most peculiar feature observable in the tortoise is the example it 
affords of having the skeleton on the outside, a characteristic found nowhere 
else save in insects and crustaceans, nor in any of these so perfectly. The tor¬ 
toise, to all purposes, is enclosed within a box, with openings at the sides to 
permit the free exercise of its head, limbs and tail. But the creature is firmly 
attached to this covering, and is unable to remove any part of the back, and 
only very slightly the shield that protects the breast. This shell is of horny 
structure and divisible into two parts, the upper being called the carapax , and 
the lower, or breast-plate, the plastron. The difference between turtle and tor¬ 
toise, in structure, is observable in that the carapax and plastron of the latter 
are inseparable, being a continuous growth, and the ribs are united through¬ 
out, whereas in the turtles the ends of the ribs retain their original width, and 
there is a difference in the composition between the carapax and plastron. 
The tortoises are devoid of teeth but possess an excellent substitute therefor 
in having very sharp, bony-edged jaws enabling them to bite with great effect. 
The neck is generally long and retractile, in some species being of apparently 
disproportionate length and yet capable of being withdrawn entirely within the 
shell and concealed, as well as protected, by the anterior part of the plastron, 
which works upon a hinge and may be opened or closed at the pleasure of the 
animal. 
In muscular strength the tortoise exceeds all other creatures, every bone as 
well as the carapax being designed with the special view of re-enforcing the 
muscles and giving extraordinary strength and vitality to the animal. The brain 
is surprisingly small and does not appear to be absolutely essential to life, if 
we are to believe the statement of the naturalist Redi, who has reported many 
strange experiments made with tortoises. Among these experiments was one to 
