88 PRACTICAL ZOOLOGY. 



3. The fore limb consists of the arm, forearm, and 

 hand. 



4. The hind limb consists of the thigh, leg, and foot. 



5. Count the fingers and toes. 



6. What differences are there between the fore and hind 

 limbs ? 



7. Open the mouth, seize the tongue with the forceps 

 and draw it forward ; observe that it is attached 

 in front, but free behind. How is such a tongue 

 used? 



8. Look closely for teeth. Where are they ? 



9. Pass a bristle tipped with sealing-wax into one of the 

 nostrils. Where does it enter the mouth ? 



10. Make a small opening in one of the tympanic mem- 

 branes, pass a bristle through this opening, and look for 

 its appearance in the mouth. The opening through 

 which it appears is the Eustachian tube. 



11. The mouth narrows back into the gullet. 



12. In the back part of the floor of the mouth is a small 

 slit, the glottis, leading to the lungs. 



13. Compare the colors and markings of the upper and 

 lower surfaces of the frog; draw dorsal and ventral 

 views of the dead specimen, naming all visible parts. 



INTERNAL STRUCTURE OF THE FROG. 



1. Cut through the skin of the abdominal wall along the 

 middle line ; turn the skin back on each side, noting 

 how loosely it is attached to the abdominal wall. 

 Cautiously avoiding any large blood-vessels, open the 

 abdomen lengthwise from the pelvis to the breast- 

 bone ; from the hinder end of this slit cut outward on 



