VERTEBRATA.. 195 



Legs always well developed. Vertebrae procoelous. Body short 

 and depressed. Oviparous. 



In the earlier or tadpole stages the Batrachia agree with 

 the Urodela ; but eventually the tail and the gills are ab- 

 sorbed, the latter being replaced by two equally lobed lungs. 

 Respiration, owing to the rudimentary ribs, is an act of swal- 

 lowing. 



The teeth are small, variously disposed, but sometimes absent, 

 especially in the lower jaw. The trunk- vertebras are few in 

 number (7-10). There are a sternum and a pelvis. The toes 

 are, with one exception, without claws ; the hind feet are often 

 webbed. The larynx is well developed. 



The skin is shed periodically, as in the serpents ; the toad 

 swallows his. The Batrachia live on insects, small fish, or 

 mollusks ; and the bigger ones are quite capable of swallowing 

 the smaller species. 



The eggs are frequently not fecundated until after they have 

 been laid. In Alytes obstetricans the female lays a chain of 

 eggs, which the male twines round his thighs until the young 

 leave the eggs. The female of Pipa americana has a soft skin 

 on the back, in which the male embeds the eggs, which then 

 closes over them. The female Nototrema has a dorsal pouch, 

 extending over the whole of the back, in which the eggs 

 are sheltered. Bony plates are found on the back of Cera- 

 tophrys. 



The three British species of this order are the frog (Eana 

 temporaria), toad (Bufo vulgaris), and natterjack (Bufo calamita). 

 The little green frog of the south of Europe is Hyla arborea, and 

 the edible frog is Rana esculenta. A Ghiiana frog with a most 

 fish-like larva, attaining a large size, is Pseudis paradoxa. The 

 larva of Pipa is tailless. 



The five or six hundred species of which this order consists 

 are very homogeneous. The subdivisions and genera [about 

 130] have been founded chiefly on modifications of the skeleton 

 and disposition of the teeth. G-iinther (in 1858) had twenty-five 

 families, Cope (in 1865) fourteen, Owen (in 1866) four, Mivart 

 (in 1869) sixteen, Car us (in 1875) seventeen, and Schmarda (in 

 1878) five the fifth, in addition to the four mentioned below, 

 being represented by Bombinator. A higher series of divisions 

 has been into Aglossa (tongueless) and Phaneroglossa (tongue 

 present), the latter again into Oxydactyla (slender toes) and 

 Platydactyla or Discodactylia (toes dilated at the tip). 



Tne following is a tabular view of Dr. Grunther's classifica- 

 tion : 



o2 



