Reptilia. 101 



of the shell ? How does it protect these parts ? Can any part of 

 the shell be moved, or is it wholly rigid ? 



EXTERNAL FEATURES OF A TURTLE. 



1. The upper part of the shell is the carapace. 



2. The under part is the plastron. 



3. Observe the large sections, or plates, marking the shell. 

 How many of these plates are there on the carapace ? How many 

 on the plastron ? How are they arranged ? 



4. Study the motions of the head, legs, and tail ; observe the 

 scales on these parts. 



5. Note the shape of the feet; for how many purposes does 

 the turtle use its feet? Are the feet of all turtles alike? Count 

 the claws ; compare the front and hind feet. 



6. With a strong pair of pinchers seize the head, pull it well 

 out, and chop it off; examine' the mouth; are teeth present? Is 

 there a tongue? Look for a third eyelid. Compare with the 

 pigeon in this point of structure. 



DISSECTION OF THE TURTLE. 



Saw through the bridge which connects the carapace and plastron 

 on each side. Carefully raise the plastron, and, keeping the blade 

 of the knife or scalpel close to its inner surface, cut away all its 

 attachments to the organs within, and remove it entirely. 



1. In front are the bones supporting the fore limbs. 



2. Behind are the bones of the pelvis, supporting the hind limbs. 

 Were these two sets of bones attached to the plastron ? 



3. A thin membrane covers the internal organs ; through it the 

 heart may be seen beating. Cautiously avoiding blood tubes, cut 

 away this thin covering, and distinguish the following parts of the 

 heart : 



a. The large, hinder part, the ventricle. 



b. In front, on each side, the two auricles. 



c. Between the auricles are blood tubes, branching toward the 



