62 



COMPARATIVE ANATOMY 



IV. EPISTERNTJM. 



Episternal structures, which are wanting in Fishes, Dipnoans 

 and recent TJrodeles, play an important part in fossil Amphibians 



Fif!. i6. — Pectobal Arch of Various Stegocephala (from the ventral side). 



After H. Crediier. 



A, Braiichiosaiirus, x 3 ; B, Pelosaurus x 2 ; C, Discosaurus, x 2 ; D, Hylono- 

 mus, X 2 ; E, Archegosaurus, x about i. Eps, episternum ; CI, clavicle ; 

 s, .scapula ; c, coracoid ; s, calcification in the sternum or in the cartilage 

 of the coracoid. 



and primitive Reptiles {e.g., Stegocephala and Palseohatteria), in 

 which, both as regards form and structure, they bear a great re- 

 semblance to the episternum of certain existing Reptiles. 



