232 



REPTILES AND BATRACHIANS 



females, however, are provided with a dorsal pouch. As 



the breeding season approaches the skin on the female's 



back folds over in the form of a horseshoe 

 in front of the vent and proceeds to 

 distend until, in some species, almost the 

 entire back forms a pouch for the re- 

 ception of the eggs. In some forms the 

 entire metamorphosis takes place within 

 the pouch, whilst in others the young are 

 liberated in a larval stage, and complete 



Fig. 20.— Noiotrema their metamorphosis in the water. In 



N. cornutun, N. oviferum, and in N. 

 testudineum, the young, up to the time 



of their liberation, breathe by means of a pair of large 



funnel-shaped membranes, connected with the first two 



gill-arches by means of a pair of 



long, thin tubes. '' '' 



marsupiatum. 



(After Gunther.) 



■^ 



\x 



J 



In the family Pelobatid^, the 

 upper jaw is toothed; the trans- 

 verse processes of the sacral vertebra 

 are strongly dilated. The pupil is 

 always vertically elliptic. The 

 family, which is represented by 

 seven genera, inhabiting Europe, 

 Southern Asia, New Guinea, and 

 Northern and Central America, 

 occupies an intermediate position 

 between the Discoglossidcs and the Bufoiiidce. 



There are two European genera, narnely, Pelodytes and 

 Pelobates ; the members of the former are easily dis- 

 tinguished in being slender and frog-like, with deeply cleft 



Fig. 21. — Young of Noio- 

 trema cornutum, showing 

 bell-shaped gills. 



(After Boulenger.) 



