436 BOULENGER. 



Brown, gray, olive, or bright green above, with dark brown or black 

 spots usually disposed with great symmetry ^ rarely without spots; 

 a dark central streak and a dark temporal blotch sometimes present; 

 tympanum often reddish or bronzy, sometimes with a central and white 

 spot; the dorso-lateral folds usually golden or bronzy; limbs with 

 large dark spots or more or less regular cross-bands; hinder side of 

 thighs yellow, spotted or marbled with black, or black with reddish 

 yellow spots. Lower parts white, throat and breast sometimes spotted, 

 marbled, or mottled with gray or brown. 



Male with the vocal sacs internal or more or less developed extern- 

 ally, but not retractile, forming loose folds behind the angle of the 

 mouth, above the arm; arms rather strongly thickened; a strong 

 pad on the inner side of the first finger, covered, during the breeding 

 season, with a wart-like gray or blackish horny layer. 



Nasal bones moderately large, separated from each other and 

 from the narrow frontoparietals; ethmoid exposed above, squarely 

 truncate in front, not produced between the nasals; zygomatic 

 branch of the squamosal not or but sHghtly longer than the posterior. 

 Pectoral arch as in R. esculenta. Terminal phalanges slightly expanded 

 at the end. 



Tadpole very similar to that of R. esculenta, the horny teeth disposed 



in Y^ series, the back broadly edged with black. 



2 



Eggs very small, only 1| millim. in diameter. Cf. Miss Dickerson's 

 book for a detailed and copiously illustrated account of the develop- 

 ment. 



Habitat. — North America, as far north as 52°, and not extending 

 west of the Sierra Nevada; Mexico and Central America as far south 

 as Costa Rica. Reaches 8000 ft. altitude in Colorado, 8500 ft. in 

 Mexico, 5000 ft. in Costa Rica. 



As is to be expected in a species of so wide a distribution, there are 

 many variations of structure and coloration, which may be regarded 

 as geographical; they cannot, however, be properly defined in the 

 present state of knowledge. Cope has attempted to put order into 

 the matter by dividing the species into four subspecies with the fol- 

 lowing definition, but he was careful to remark that they "pass into 

 each other by occasional intermediate specimens " : — 



a. sphenocephala, Cope {oxyrhynchus, Leconte). Head entering 



6 Sometimes it is quite the reverse, as shown in a female from Cuttyhunk, 

 Mass., which has 3 large spots on one side of the upper surface (1 palpebral, 2 

 dorsal) and only one (dorsal) on the other. 



