106 



COMPARATIVE ANATOMY 



On the dorsal side of the chondrocranium. are a large median 

 anterior foiitanelle 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. 



Premaxilla 



Septomaxilla 



Nasal 



Maxilla 



Alar cart. 



Oblique cart. 



Ant. maxil- 

 lary process 



II . 



Pterygoid 

 cart. 

 Ill 



V, VII 



Annalus 

 tympanicw 



Artie pro- 

 cess of 

 quadrate 



And. capsule 



Exoccipital 



FIG. 78. SKULL OF A YOUNG Rana temporaria, 2 CM. IN LENGTH, JUST AFTER 

 METAMORPHOSIS, FROM THE DORSAL 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 gray ; 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 zygomatic 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 



Pterygoid 

 Frontoparietal 



Columella 



Quadratojugal 

 Paraquadrate 



