COMPARATIVE ANATOMY 



essentially different and much more complicated development 

 and cannot in any way be directly derived from that ot tailed' 

 Amphibians. 



1il)rl 



^pbrl 



Koir. 



kb: 



jEphrl 



Fig. 67. — Hyobkakchial Appakatxjs of Urodeles. A, Axolotl (Sirejlon stage 

 of Anibly stoma) ; B, Scdamandra maculota ; C, Triton fristatuts; D, Spdtrpt-s 



f II sells. 



Bhr, I, II, first and second basibranchial ; KeH, ceratohyal ; HpH, hypohyal ; 

 Kehi- 1, II, first and second ceratobranchial ; Ephr 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 motUh, 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 



