Identify the bones according to the directions given 

 in section 17. Make a drawing of the ventral aspect, 

 noting any differences between this type of girdle and 

 that fotind in the frog. 

 (19). Sacrum (gth vertebra) of a frog — The lateral processes 

 are known as diapophyses, which in the frog are 

 cylindric or "not dilated." Make a drawing of the 

 dorsal aspect. The centrtim is on the ventral aspect, 

 and the diapophyses point caudad. 

 (20). Sacrum of the common toad — This is an example of the 



dilated diapophyses. Draw the dorsal aspect. 

 (21). Make a drawing of the sole of the right foot. 

 (26). Egg cluster of No. 25. Make a drawing of the cluster 

 and the branch to which it is attached. Represent a 

 few eggs as if in the periphery of the cluster to show 

 the enveloping jelly and the relabion of the eggs to 

 each other. Do not remove the eggs from the jar. 

 Compare with No. 15. 

 (27). A series of specimens to illustrate the larval develop- 

 ment of the frogs and toads. 



(a). On the left side of the body, below and behind 

 the eye, is a cleft, the spiracle, opening 

 through a thin walled tube. After the loss of 

 the external gills, internal gills are developed 

 and the respiratory stream passes in at the 

 mouth, over the internal gUls and out at the 

 spiracle. Is the tadpole symmetrical with 

 regard to the spiracle? Determine the 

 natiu"e and position of the vent. On either 

 side of the vent note the rudiments of legs. 

 Make a drawing of the left side of the speci- 

 men. 

 (b). Mouth parts of a tadpole. Examine the mouth 

 of stage a with a hand lens for the general 

 arrangement of the parts. Note : the broad 

 expanse of lips bordered by a fringe ; the jaws 

 covered by a horny substance; the rows of 

 fine teeth on the lips above and below the 

 mouth. With a microscope study more 

 carefully the par bs of a specimen mounted in 

 balsam. Make an enlarged drawing. 

 17 



