CADUCIBRANCJIIATA. 1 9 



Branchial apertures upon the neck open*, (a) 



Derotremata. 

 Branchial apertures closed in adult, (b) . 

 (a) Anterior metacarpal bones three. 



Amphiumida. 



(a) Anterior metacarpels four. . . Menopomida. 



(b) Anterior metacarpels four.SALAMANDRiDA. 



AMPHIUMIDA. 



Skull elongated ; parasphenoid and vomer united, den- 

 tigerous on their anterior margin; palatine bones want- 

 ing; prefrontals and pterygoids present; praemaxillae 

 and dentaries dentigerous; maxillae and nasalia large; 

 praemaxillaries united to form a single piece ; parietals 

 laterally prolonged, not contiguous with the prefrontals ; 

 fronto-temporal arch none or incomplete; occipital con- 

 dyles pedicellate; basihyal cartilage present; a pharyn- 

 geal slit present on each side of the neck; branchial 

 arches four persistent; gills caducous; eyelid circular; 

 vertebrae amphicoelous; carpus and tarsus cartilaginous ; 

 pelvic and pectoral arches and limbs developed, but 

 small; anterior digits two or three; fourth finger with a 

 single phalanx. 



*Cryptobranchus forms an exception, being without bran- 

 chial apertures. 



