No. 6i6] THE PHY LOGS NY OF THE CAUBATA 423 



Several characters divide them into two series, which 

 should, I think, rank as superfamilies. 



1. Prearticular bone. Present in Cryptobranchidcs and 



Hynobiidce, and absent in Ambystomidce, Salaman- 

 dridcc and Plethodontidce. 



2. Second epibranchial. Present in CryptohramhidcB 



and Hynohiida', and absent in AmhystomidcE, Sal- 

 awandridcc, and Plethodontida'. 



3. First ceratobranchial and first epibranchial fused into 



a single cartilaginous rod in C nipfol>}-(n>(liida' and 

 in Hynohiidcc. Separate elcinciits in Ainln/sfo- 

 ' mid(C, Salaniandndcc (exc. Salanui^idid, whore all 

 parts fuse), and Pletliodont'uhc. 



4. Nasals meeting in median line and premaxillae without 



nasal process in Crypt oh ranclddce and Hynohiida:. 

 Nasals separated by nasal spines of premaxillfr in 

 Amhi/sfoniida\ Salaw<nidnd<c, and Plethodontida' 

 (exc. Pscuilotnin)! , where nasals overlap premaxll- 

 lary spines). 



5. Pubotibialis muscle fused with puboischiotibialis in 



Crypt oh ranchidcc. The two nuiscles are separate 

 in all other salamanders (Noble, 1!)22). 1 have 

 ascertained that the two are fused in IJynohiu^ 

 and i?i Oin/chodacI i/hts. 



6. Larva^ of A »ihi,sfnw;d. , Salawaadndu . and Plrthn- 



douCdn have the tir-t eeratohi'ancliials fused with 

 the seeond l)asi])i-anehial (Smith. IDl'D). Tliis t'u- 



or of ffni/nhiirln . 

 Within tlir snpei'lamilv Salanxnid roidra the AniJn/sto- 

 mida and tlie Sn! n unn<d , ,dn are about parall-l. The 

 Ion- poMerie,r pron-. of the pp-voni.r diM in-ul^he. the 

 ^^atauumdndn , and a< the ] .a raspheiioid tooth patches of 

 PJ,tl,<u]n,<fid., aiv tin- unu']>li.^h.i:iral e.piivalmt ot this 

 l)n)e.'s^ (Wilder. l!»L'i>) it is iwohahlr that s.niie primi- 

 tiNe Sah-unandrid ( ha\ in- tie- tuo niie ..lennuU^ free) 

 gave rise to the much degenerate Plethodontida'. Tlie 



