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Family I. RANOIDEA. 



CHARACTERS. 



I. There are always teeth in the upper jaw and palate, between the posterior 

 nares; the latter are minute, and variously grouped. 



II. The extremities of the fingers and toes are free, and never dilated into 

 a disk. 



III. The tympanum is always visible. 



IV. The males are provided with vocal vesicles at the throat, communicating 

 internally with the mouth, and in some they pass out of openings at the sides of 

 the jaws when distended, but not in others. 



Remarks. This family embraces a great many genera, three only of which 

 have as yet been observed as inhabitants of the United States — Rana, Cystingna- 

 thus, and Scaphiopus. 



