70 



SKELETON OF THE FROG. 



The chief changes which take place in the conversion 

 of the cartilaginous skull of the larva to the ossified one 



Fig. 12. 



SKELETON OF THE FROG (Rana eaculento). 



of the imago, or perfect frog, are seen in the shape and 

 relative position of the hsemal arches and their append- 

 ages — i. e., of the maxillary, mandibular, hyoid, and sca- 

 pular arches. The maxillary arch expands in breadth, 



