82 STUDIES OF ANIMAL LIFE. 



5. The Teeth. (Feel for them with your finger or 



with a needle.) 



a. Are teeth present on the upper jaw ? On the 



lower jaw ? On the roof of the mouth ? (Com- 

 pare with a skeleton of a frog.) 



b. Does the frog chew its food ? 



What is the probable use of the teeth ? 



6. Identify the following openings into the mouth 



cavity, (Dem.) — 



(a) the oesophagus ; 



(J) the internal nostrils ; 



(c) the eustachian tubes ; (Their openings are near 

 the angle of the jaws and lead to the ear.) 



(d^ the glottis, the opening of the wind pipe (tra- 

 chea). It is slit-like and surrounded by car- 

 tilage. 



7. Indicate the position of these openings and of the 



jaws, teeth and tongue in a sketch. (Represent 

 the mouth wide open.) 



E. The Fore Liimbs. 



1. Observe the division of the limb into the upper arm, 



(the proximal segment) the forearm and the 

 hand. 



2. How many fingers are there on each hand ? 



3. What are the uses of the fore limbs ? (Observe the 



frog while at rest and while in motion.) 



4. How are the fore limbs adapted to their uses ? 



5. Why cannot a frog jump by means of its fore limbs ? 



6. Is there any advantage in the way the frog "toes 



in"? 



7. Make an outline drawing of a limb, showing its 



parts. 



