76 MANUAL OF NATURAL HISTORY. 



II. ORDER — Gill-lunged Amphibians (Amphipneurta). 



Body elongate, naked, smooth ; feet 4, or 2 ante- 

 rior only, rudimentary ; toes short, weak ; tail com- 

 pressed, persistent ; eyes small ; eyelids none ; res- 

 piration aquatic by means of persistent external 

 branchiae co-existing with rudimentary lungs. 



1. Family. — Proteans (Proteidae). Legs 4, weak ; 



tail compressed ; gill-flaps distinct ; gills large ; 

 palatine teeth in two long series on front 

 edge of vomerine bones. 



2. Family. — Sirens (Sirenidae). Legs 2, anterior ; 



body sub-cylindrical ; operculum none ; gills 

 small; palatine teeth in numerous cross series 

 on vomerine bones. 



III. ORDER. — Long-tailed Amphibians (Urodela). 



Body elongate ; tail long, persistent ; limbs 4, 

 weak ; skin naked, smooth, or warty ; ears hidden ; 

 respiration at first aquatic by external branchiae, 

 afterwards atmospheric by cellular lungs. 



1. Family. — Salamanders (Salamandridae). Tail 



compressed or round (remains compressed 

 in aquatic species) ; palatine teeth in two 

 diverging series, one on inner posterior edge 

 of each elongate palatine bone ; sphenoid 

 toothless ; females of some viviparous. 



2. Family. — Smooth-Salamanders (Molgidae). Head 



depressed ; tongue large ; tail rounded ; pala- 

 tine teeth in two converging series along 

 outer and posterior edge of each elongate 

 palatine bone ; sphenoid toothless. 



