GENERAL ANATOMY 



85 



also in the other Lissamphibia, while supratemporals and siipra- 

 occipitals are absent. There is, however, a pair of bones which 

 represent either the postorbitals or the postfrontals, perhaps 

 both, of the Stegocephali. The quadrato-jugal arch is enormously 

 developed, and by reaching the parietal, frontal, and postorbito- 

 frontal bones (which latter occur only in Ichthyojjhis and 

 UraeotypJilus) and the maxilla, extends over the whole of the 

 orbito- temporal fossa. The squamosal is completely fused with 



Fig. 1.3. — )i\\\\\ oi Tchthyo2)liis ghdinosa. x 3. (After Sarasin.) A, Lateral. B. ventral. 

 C, dorsal view. A, Posterior jirocess of the os articulare ; Ca, carotid foramen ; C'A, 

 choana or posterior nasal opening ; F, frontal ; J, jugal ; Lo, lateral occipital ; 

 Mx, maxillary ; X, nasal ; Xo, nostril ; O, orbit ; /', parietal ; Pa, palatine ; Pin, 

 premaxillary ; Pof, postfrontal ; Prf, prefrontal ; Pt, pterygoid ; Q, qnadrate ; -S', 

 squamosal ; St, stapes ; T, tentacular groove ; Vo, vomer ; X, exit of vagus nerve. 



the (|uadrato-jugal. The stapes has the typical stirrup-shape, is 

 even perforated by an artery, and articulates distally with the 

 shaft of the quadrate (as in the snakes). The maxilla is very 

 large and broad. Owing to its broad junction with the quadrato- 

 jugal arch, tlie prefrontal and frontal, tlie orbital fossa is reduced 

 to a very small hole, or the maxilla completely covers the eye. 

 Somewhere between the latter and the nares the maxilla is 

 perforated by the tentacular groove. The periotic bones are 

 represented by the prootics and epiotics ; they fuse with 

 the lateral occipitals and with the parasphenoid. The whole 



