AMPHIBIA. 



279 



gap appears between the cranium and the quadrat ojugal-malar 

 arch. This latter arch is entirely absent in the urodeles. The 

 roof of the mouth is formed by vomers, palatines, and a para- 

 sphenoid, the latter element not reappearing in the higher 

 groups. In the caecilians the parasphenoid fuses indistinguish- 

 ably with occipital elements. All of these bones may bear teeth, 

 as may also premaxillaries and maxillaries, the latter element 



FIG. 279. Skull of Ichthyophis glutinosus, after the Sarasins. b, basal, com- 

 posed of the coalesced parasphenoid and the occipitals ; e, ethmoid ; f, frontal ; 

 j, jugal ; mp, maxillopalatine ; n, nasal ; /, parietal ; pf, prefrontal ; pm, premaxil- 

 lary ; po, postfrontal ; pt, pterygoid ; s, suspensorium ; st, stapes; t (in front), 

 turbinal ; (behind) tentacular groove. 



occasionally being absent. The quadrate is overlaid by a 

 squamosal. 



In the shoulder girdle coracoid, procoracoid, and scapular 

 elements are formed ; in the urodeles the procoracoid usually 

 extends directly forward, but in the anura the ventral ends are 

 connected by an epicoracoid, and the procoracoid is more or less 

 completely replaced by a membrane bone, the clavicle. The 

 amount of ossification varies in different forms. The pelvis is 

 characterized by the development of the ilium, which is very 

 strong in the anura. Ventrally there is frequently a continu- 

 ous ischiopubic plate in which a distinct pubis rarely ossifies. 

 Epipubic processes are common in the urodeles. The limbs 



