l68 VERTEBRATE ANIMALS OF THE UNITED STATES 



About i,2oo species of Salientia are known, which occur in all the 

 geographical regions of the earth, about 60 species being in the United 

 States, grouped in 6 families. 



On the Identification of the Salientia.- — The descriptions of frogs 

 and toads in this book apply to both adults and larvae, and inasmuch as 

 the animals in these two stages of development differ radically in 

 form and appearance, the descriptions of the two stages are given 

 separately. 



I. The Adult. — There is a general uniformity in the shape of the 

 body of the various species of frogs and toads, and the most important 

 descriptive features are the following; the length in millimeters and 

 color of the body, the size and shape of the head, the length of the hind 

 legs, the character of the digits, the number of which is four in the 

 fore foot and live in the hind, the character of the skin, whether it 

 is smooth, tubercular or warty, the presence and character of the paro- 

 toid gland, the tympanum and the teeth. For a complete analysis of 

 the main group several internal structures are important—the ribs, 

 vertebrae, sacrum and pectoral girdle. 



Key to the Families of the Salientia 



ai Ribs present 5. Discoglossidce. 



a2 Ribs absent. 



bi Pupil of eye vertical; parotoid glands present 2. Pelohatidce. 



b2 PupU of eye horizontal or round. 



Ci Parotoid glands present (Fig. 81) toads 3. Bufonidce. 



C2 Parotoid glands absent. 



di Expanded adhesive disks at ends of digits; tree toads 



(Figs. 88 and 89) 4. Hylid(B. 



d2 No such disks present. 



ei Upper jaw with teeth ; frogs 5. Ranidce. 



ti Upper jaw without teeth 6. Brevicipitidce. 



Family i. Discoglossidae.^ — Ribs present; vertebrae opisthocoel; 

 tongue with but little movement; larvae with a midventral spiracle: 

 5 genera, i in New Zealand, 3 in the Palearctic region and i in western 

 America. 



Ascaphus Stejneger. Tympanum and Eustachian tube wanting; 

 tongue free behind; sternum cartilaginous; maxillary and vomerine 

 teeth present; parotoid gland well developed: i species. 



A. truei Stej. Color reddish brown or slate gray above, with a few 

 blackish markings, and whitish beneath; a black streak from the nostril 

 through the eye and along the lower border of the parotoid gland; 



