118 



THE VERTEBRATE SKELETON. 



in some forms, like Scymnus and Galeus, a joint is indicated, 

 and in others, such as the Rays, one is fairly well developed. 



FIG. 16. A. SKULL OF Notidanus 



(Brit. Mus.). B. SKULL OF 



Cestracion x (after GEGENBAUB). In neither case are the branchial 

 arches shown. 



6. Meckel's cartilage. 



7. teeth. 



1. rostrum. 



2. olfactory capsule. 



3. ethmo-palatine process. 



4. palatine portion of palato- 



pterygo-quadrate bar. 



5. quadrate portion of bar. 



8. labial cartilage. 



9. hyomandibular. 

 10. postorbital process. 



II. optic foramen. 



The cranium in Elasmobranchs is never bony, though the 

 cartilage is sometimes calcined. It is drawn out laterally 

 into an antorbital process in front of the eye, and a post- 



