THE VERTEBRATE BODY 



141 



arches form the vertebral canal containing the spinal cord; 

 and below, the transverse processes, ribs, and sternum surround 

 the anterior portion of the coelom. (Figs. 95, 101, 105.) 



Olfactory capsule^ 

 Sphenethmold^ 



Fontanelles,, 



Anterior 



corn a of 



byoid 



Fontanelles 



Probtlc 



Otic 

 process 



6ospen; 



eorlum 

 Exocclpltal 



Cervical 

 vertebra 



Transverse 

 process 



,Premaxilla 

 , Vomer 



Sacral vertebra 



Urostyle 



Acetabulum 



Calcaneum 



Astragulus 



Fig. 103. - - Skeleton of the Frog. Dorsal aspect; the left half of the shoulder 

 girdle and the left fore and hind limbs are removed, as also are the membrane 

 bones on the left side of the skull. Permanently cartilaginous parts dotted. 

 (After Howes, slightly altered.) 



The Vertebrate head, containing the anterior end of the ali- 

 mentary canal and respiratory passages, and also the brain and 

 chief sense organs, is protected in the lower Fishes by a case of 

 cartilage. In higher forms the cartilage is replaced by a bony skull 

 which articulates with the first vertebra of the backbone. Jaws, or 

 supporting structures of the mouth, are attached to the skull. 



