Introduction 



II. Superfamily Firmisternia. 



The two halves of the shoulder-girdle meet in front and 

 unite (coracoids and epicoracoid cartilage), so that the 

 chest is not capable of expansion. (Fig. 5.) 

 A. Sacral diapophyses dilated. 



Vertebras proccelous, ribs absent, teeth absent or pres- 

 ent. Family 6. Engystomahda (Engystoma pp. 48 and 

 1 66). B. Sacral diapophyses cylindrical. 



Vertebrae precocious, ribs absent, teeth on upper jaw. 

 Family 7. Ranidce (Frogs), pp. 48 and 171. 



Family I. Discoglossida 



This is the most primitive family of the Salientia, resembling 

 the Salamanders in the possession of ribs and in other detailed 

 characteristics of the skeleton. The tongue is round and only 

 slightly free behind, so that it cannot be extended for the capture 

 of food. At the breeding season the clasp of the male is lumbar 

 or inguinal, as among the Salamanders and the Pelobatidas. The 

 tadpoles have the breathing-pore situated on the midline below, 

 instead of on the left side as in all other families of the Salientia. 



Until 1897, when a new genus of the Family was found at 

 Humptulips, Washington, the Discoglossidas contained only four 

 genera, and were supposed to be unusually limited in distribution. 

 They were reported from Europe, southwestern Asia, northern 

 Africa, and the island of New Zealand only, never having been 

 found in the Western Hemisphere, or in tropical Africa, Asia, or 

 Australia. (Refer to p. 51.) 



Family II. Pelobatidce 



This family, related to the Discoglossidas below and the Bu- 

 fonidae above, also shows some primitive characteristics of struc- 

 ture, and the clasp at the breeding season is inguinal. The mem- 

 bers of the Family are strictly nocturnal, as is evidenced by the 

 vertical pupil of the eye. They are burrowing in habit. The 

 foot is unusually thick and leathery and is provided with a large 

 sharp-edged digging spur (inner sole tubercle). 



The Family is well represented in North America and Mexico 

 and in the Eastern Hemisphere, with the exception of tropical 

 regions. Seven genera are known and about twenty species. 

 North America has four representatives of the one genus Scaphi- 

 opus. (Refer to p. 53.) 



8 



