SUGGESTIONS.—Because of the ease with which a tortoise or a turtle may be caught and their movements and habits studied, it is suggested that one of these be studied as an example of reptiles. Besides a live specimen, a skeleton of one species and the shells of several species should be available. [Illustration: FIG. 266.—EUROPEAN POND TURTLE (_Emys lutaria_). (After Brehms.) ] The =body (of a turtle or a tortoise) is divided= distinctly into _regions_ (Fig. 266). Is there a head? Neck? Trunk? =Tail=? The trunk is inclosed by the _so-called shell_, which consists of an upper portion, the _carapace_, and a lower portion, the _plastron_. How are the other regions covered? What is the shape of the head? Is the mouth at the front, or on the under side? Where are the _nostrils_? Are the motions of breathing visible? Is there a beak or snout? Do the jaws contain _teeth_? Do the =eyes= project? Which is thinner and more movable, the upper or the lower lid? Identify the third eyelid (_nictitating membrane_). It is translucent and comes from, and is drawn into, the inner corner of the eye. It cleanses the eyeball. Frogs and birds have a similar membrane. The circular =ear= drum is in a depression back of the angle of the mouth. What other animal studied has an external ear drum? The tortoise has a longer, more flexible =neck= than any other reptile. Why does it have the greatest need for such a neck? Is the skin over the neck tight or loose? Why? Do the =legs= have the three joints or parts found on the limbs of most vertebrates? How is the skin of the legs covered? Do the toes have _claws_? Compare the front and the hind feet. Does the tortoise slide its body or lift it when walking on hard ground? Lay the animal on its back on a chair or a table at one side of the room in view of the class. Watch its attempts to right itself. Are the motions suited to accomplish the object? Does the tortoise succeed? What are the prevailing =colours= of turtles? How does their colouration correspond to their surroundings? What parts of the tortoise extend at times beyond the shell? Are any of these parts visible when the _shell is closed_? What movements of the shell take place as it is closed? Is the carapace rigid throughout? Is the plastron? [Illustration: FIG. 267.—SKELETON OF EUROPEAN TORTOISE. _C_, rib plates; _M_, marginal plates; _B_, plastron; _H_, humerus bone; _R_, radius; _U_, ulna; _Fe_, femur. ]