450 GENERAL ZOOLOGY 



Order 1. Apoda. Blind burrowing forms, without limbs. The 

 skin contains small bony scales. 



Example: Ichthyophis glutinosus, about 1 ft. in length. 

 Found in India and Ceylon. 



Order 2. Caudata (Urodela). Salamanders and related 

 forms. An elongate body with a well-developed tail; usually 

 two pairs of limbs; teeth may be present on the maxillary and 

 premaxillary bones, the vomer, pterygoid, parasphenoid, and 

 mandible; gills are permanent in some, lost in others at meta- 

 morphosis. There is no tympanum. 



Examples : Necturus maculosus, the mud puppy, is completely 

 aquatic and has permanent gill slits and external gills, and also 



Fig. 270. — Ambystoma maculatum, with external gills which disappear at meta- 

 morphosis. 



lungs. Length about 1 ft. Common in rivers and lakes of 

 Eastern United States. Cryptobranchus alleganiensis, the hell- 

 bender, has internal gills and lungs. Length about 1}4 ft. 

 It is aquatic and is common in Eastern United States. Amby- 

 stoma maculatum, the spotted salamander (black body with 

 large bright-yellow spots), is terrestrial but returns to water to 

 lay its eggs. The adult has lungs but no gills. Ambystoma 

 opacum, the marbled salamander, lays eggs on land in the fall. 

 Rains wash the eggs into water where larvae are hatched and 

 complete their development. Eurycea bislineata, a common 

 lungless salamander, has neither gills nor lungs in the adult 

 state. Siren lacertina, the mud eel, an aquatic form, breathes 

 by gills, and lacks hindlegs. Length about 2% ft. Found in 

 Southeastern United States. Proteus anguinus, a blind sala- 

 mander about 1 ft. in length, found in caves in Austria. 

 Order 3. Salientia (Anura). Frogs and toads. A tail is 

 absent, the caudal vertebrae being transformed into the uro- 

 style. The posterior pair of legs modified for leaping; a 

 tympanum is present, level with the surface of the head; males 



