86 



COMPARATIVE ANATOMY 



essentially different and much more complicated development, 

 and cannot in any way be directly derived from that of tailed 

 Amphibians. 



flpbrl 



K2T 



-KeJT 



Ktff, 



FIG. 67. HYOBRANCHIAL APPAKATUS OF URODELES. A, Axolotl (Siredon stage 

 of Amblystoma) ; B, Salamandra maculota; C, Triton cristatus; D, Spelerpes 



fuscus. 



Bbr, I, II, first and second basibranchial ; Ke.ff, ceratohyal ; HpH, hypohyal ; 

 Kebr I, II, first and second ceratobranchial ; Epbr I to IV, first to fourth 

 epibranchial ; KH, KH } , small anterior and posterior pairs of cornua ; 

 O.th, part of skeleton of larynx ; G.th, thyroid gland. 



A suctorial mouth, provided with labial cartilages and horny 

 jaws, is present in the larva. An advance on Urodeles is seen in 

 the formation of a tympanic cavity which is closed externally by a 

 tympanic membrane, while internally it opens into the mouth by an 



