106 



COMPARATIVE ANATOMY 



On the dorsal side of the chondrocraniutn are a large median 

 anterior fontanelle or fenestra, and a smaller paired posterior 

 fontanelle, and the cartilage becomes replaced by bones in the 

 occipital, auditory, and ethmoid regions (Figs. 77 and 78). There 

 are paired exoccipital and prootics and a sphenethmoid, the 

 lateral parts of which correspond in position to the orbitosphenoids 

 of Urodeles, and which encircles the whole skull ; it also forms a 

 front wall to the cranial capsule, perforated by the olfactory nerves. 



Alar cart. 



Oblique <:<trt 



A at. 



/"/// process 



II 



/'>< i'//yoid 

 cart. 



Ill 



V, VII 



Aiunthi-". 



Prtmaxilla 



Septonmx'Ma 



Nasal 



Max if /a 



Artie pro- 



cess of 

 quadrate 



Pterygoid 



Frontoparietal 



f- Columella 



Quadratojugal 

 Paraquadrate 



Aud. 1-npxule 



Exoccipital 



FIG. 78. SKULL UK A YOUNG Raua dmporaria, 2 CM. IN LENGTH, JUST AFTER 

 METAMORPHOSIS, KROM THE DOKSAL SIDE. THE INVESTING BONES ARE 

 REMOVED ON THE LEFT SIDE (x ABT. 11.) After Gaupp, from a model by 

 Fr. Ziegler.) 



Cartilage blue ; replacing bones ymy ; investing bones yellow. 



The frontal and parietal of either side are as a rule fused, 

 thus giving rise to a frontoparietal. The maxillary bar grows 

 backwards much further than in Urodeles, and becomes connected 

 with the suspensorium by means of a small intermediate bone, the 

 quadratojugal, or quadratomaxilla (Figs. 77 and 78). There is 

 thus a lower sygomatic arch (cf. p. 98) ; an upper zygoma like 

 that of many Urodeles is never developed, and consequently 

 the temporal region is uncovered by skeletal parts. The palato- 

 quadrate is united anteriorly with the cartilaginous nasal capsule 



