232 



Order ANTJRA or ECAUDATA. Tailless when adult. Pore and hind 

 limbs always present. Adults without gills. 



Examples, Bufo (Toad). Without teeth on jaws. Eggs 

 laid in strings. Tadpole larva. 



Alytes (Obstetric Frog). The male carries, 

 around his thighs, the strings of developing 

 eggs. 



Rana (Frog). See pages 232 to 238. Eggs laid in 

 masses. Tadpole larva. 



Pipa (Surinam Toad). Tongueless. Eustachian 

 tubes open into pharynx by a common opening. 

 The eggs are transferred to pockets in the 

 skin of the back, and there develop, hatching 

 out as miniature adults. 



Order APODA or GYMNOPHIONA. Worm-like, limbless, burrowing 

 forms, with rudimentary eyes. Examples of adaptation to 

 environment. 



Examples, Hypogeophis. Embryo has gills which atrophy 

 before hatching. 



Ichthyophis. Embryo has gills which atrophy 

 before hatching. 



The Frog (Rana). 

 A Type of the Class Amphibia. 



Give a short Account of the External Features of the Frog. 



The broad and flattened head is continuous with the 

 short and stout trunk, which has a characteristic hump- 

 back (sacral prominence), formed by the junction of the 

 pelvic girdle with the vertebral column ; neck and tail are 

 absent. The limbs are cheiropterygia. (See page 194.) 

 The fore-limbs are short ; the preaxial digit (pollex or thumb) 

 is rudimentary. At the breeding season, the male has a 

 swelling or cushion on the inner side of each hand. The 

 hind-limbs are long (ankle elongated) and the toes are 

 webbed for swimming. On the base of the hallux or " great 

 toe " there is a horny knob, the calcar. The mouth is 

 wide; above it are the two small external nares (nostrils). 

 The eyes are large ; each has two eyelids and a nictitating 

 membrane or third eyelid. Behind the eye on each side 

 is a circular area, the tympanic membrane. At the end of 



