162 



ZOOLOGY. 



view of the skull (fig. 81, B) we see a pair of vomers bearing 

 teeth, a pair of palatines, and a pair of pterygoids (which 

 palatines and pterygoids, we may note, unlike those of the 



Fig. 82. SIDE VIEW OF SKULL OF TADPOLE. 

 About the same stage as Fig. 80, B. 



rabbit, are membrane-bones), and a great median dagger- 

 shaped parasphenoid. These two figures, and fig. 83, which 

 shows the same bones in side view, should be carefully 

 mastered before the student proceeds with this chapter. 



Fig. 83. SIDE VIEW OF SKULL OF ADULT FROG. 

 Shading as in fig. 81. (After Howes.) 



The cartilage and cartilage-bones are distinguished from 

 membrane-bones by shading (but the quadrato-jugal has 

 been wrongly shaded throughout). 



5. Visceral Arches. Turning now to fig. 82, we 

 have a side view of a tadpole's skull. On the ventral side 



