MANUAL OF NATURAL HISTORY. 75 



IV. CLASS— AMPHIBIANS (Amphibia). 



Eespiration atmospheric or aquatic ; cold-blooded; 

 skeleton bony ; skin naked ; lungs cellular ; heart 

 trilocular. Most (if not all) undergo a transforma- 

 tion or metamorphosis after birth; re-production 

 oviparous ; eggs with a soft shell. 



I. OKDEK. — Tail-less Amphibians (Anoura). 



Body short, broad, depressed ; feet wanting during 

 tadpole state, afterwards 4, hinder ones longer ; 

 tail before metamorphosis long, compressed, after- 

 wards wanting ; tympanum open or hid. 



1. Family. — Frogs (Ranidse). Body tapering ; head 



flat ; hind legs extremely long ; feet webbed ; 

 skin smooth ; teeth on upper jaw and palate, 

 minute ; tympanum open. 



2. Family. — Toads (Bufonidae). Body bulky; hind 



legs slightly elongated; skin covered with 

 warts ; no teeth ; tympanum open ; avoid 

 water. 



S. Family. — Palmate-Batrachians (Dactylethridse), 

 Body short or oval ; skin smooth or tubercu- 

 lated ; tongue wanting or distinct ; teeth 

 minute or partly absent ; tympanum hid ; 

 hind feet broadly palmate ; toes pointed. 



4. Family. — Cell-backed Toads (Pipidse). Body flat- 

 tened horizontally ; head triangular ; tongue 

 wanting ; no teeth ; skin granulated ; tym- 

 panum hid. In females, during fecundation, 

 skin of back forms cells, in which the eggs 

 are hatched. 



