SKULL 



101 



separated by wide spaces ; and even where connected sheets 

 of cartilage are present, they are very delicate and thin. At the 

 same time the skull nearly resembles that of Urodeles (more 



Cp 



FIG. 74. HYOBRANCHIAL APPARATUS OF URODELES. A, Axolotl (Siredon stage 

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



fuscus. 



Cp, Cps, O.th, basihyobranchial or copula ; G.th, thyroid gland ; Hpbr. I and //, 

 first and second hypobranchial ; HpH, Fad I, hypohyal ; Kebr. I IV, first 

 to fourth ceratobranchial ; KeH, ceratohyal ("anterior cornu" of hj^oid in 

 Caducibranchs the "posterior cornu " being made up of Hpbr I and // and 

 Kebr I). Rod. II arises in Salamandra secondarily during metamorphosis. 



especially perennibranchiate forms) in spite of a considerable 

 reduction in its parts especially in the occipital, auditory, and 

 orbital regions, as well as of the peculiar and characteristic 



