THE FROG 27 



brane. Do the eyes have lids? How many? Which 

 moves in the living frog? Draw the head from the side. 



2. Trunk. Note the shape and the differences in the 

 dorsal and ventral sides. 



3. Limbs. Note the number and arrangement. In the 

 hand. How many digits or fingers? The hind limb is 

 fore limbs the following divisions occur: arm, forearm, 

 divided into thigh, leg, and foot. How many digits? - How 

 is the leg adapted for swimming? Compare with the fore 

 limb in length and number of digits. Draw both fore and 

 hind leg. 



4. External Apertures. Note the position, shape and size 

 of the following: mouth, anus, nostrils. 



II. Mouth Cavity. 



Open the mouth to its full extent, cutting the corners of 

 the jaw if necessary. Are there lips? Is there a tongue? 

 What is its shape, size and mode of attachment? Where, 

 are the teeth found? Teeth on the jaw bones are called 

 maxillary teeth, those on the roof of the mouth are vomerine 

 teeth. Pass a bristle through the outer nostrils and observe 

 the inner or posterior nostrils. Where are they found? 

 Pierce the tympanic membrane and pass a blunt probe into 

 the, ear; in the mouth cavity the place where the probe 

 appears is the opening of the Eustachian tube. 



In the posterior floor of the mouth just at the end of the 

 tongue is a slit, the glottis, opening into the trachea and 

 lungs. Its margin is stiff and cartilaginous, and the opening 

 is closed except when air is passing. The esophagus lies 

 dorsal to the glottis. Compare with the latter. 



Make a drawing of the mouth cavity, showing all the 

 points referred to. 



