How many axial plates? How many costal (rib) plates? How many border plates? Which plates are largest? Smallest? Do the horny plates overlap like shingles, or meet edge to edge? Is there any mark where they meet on the bony shell? Basing it upon foregoing facts, give a connected and complete description of the structure of the carapace. Compare the skeleton of the turtle with that of the snake, and correlate the differences in structure with differences in habits.
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Fig. 269.—Plan of Reptilian Circulation. See arrows.
Draw the tortoise seen from the side or above, with its shell closed, showing the arrangement of the plates.
Place soft or tender vegetable food, lettuce, mushroom, roots, berries, and water, also meat, in reach of the turtle. What does it prefer? How does it eat? It has no lips; how does it drink?
Study the movements of its eyeballs and eyelids, and the respiratory and other movements already mentioned. State a reason for thinking that no species of land animals exists that lacks the simple power of righting itself when turned on its back.
Fig. 270.—Reptilian Viscera (lizard).
lr, windpipe; h, heart; lu, lungs; ln, liver; ma, stomach; dd, md, intestines; hb, bladder.
Tortoise, Turtle, Terrapin.—The turtles belong to the order of reptiles called chelonians. No one
