Rana Aurora 



base of first finger greatly thickened in male (Fig. 258); tuber- 

 cles under finger-joints fairly conspicuous. Foot not thick, 

 web delicate, with two joints of fourth toe free; inner sole 

 tubercle'small, outer small or lacking. (Fig. 259.) 



Range: Rana aurora occupies the Pacific Slope. It is 

 reported from Washington, Oregon, and California. In Cali- 

 fornia, where Rana Drayionii is the common frog, Rana aurora is 

 said to be found in the high Sierras only; in Oregon and Wash- 

 ington, it is abundant, but is less so in many parts of these 

 states than is Rana pretiosa. 



Rana aurora is a delicately formed, smooth frog, less hardy 

 than most frogs of North America. (See Figs. 258 and 259, also 

 Colour Plate XIV.) It is shy and wild, and difficult to keep in 

 captivity, except in a perfect imitation of its environment. In 

 such a place, it seems to enjoy equally sitting under the shade 

 of ferns or in the water, and eats earth-worms greedily. Both 

 male and female give high-pitched, jerky cries, expressing fright, 

 when taken in the hand. One unusually large specimen opened 

 his mouth wide and gave a prolonged high-pitched scream, remind- 

 ing one of the similar sound produced by the Common Bullfrog. 



Judging from the radical difference in the sizes of the frogs 

 to be found in the spring, this frog requires four or five years to 

 become full-grown. It changes colour rapidly, from dark rich 

 browns to delicate shades of rosy tan. Rana aurora is a delicate, 

 timid-looking frog, but, notwithstanding the promise of its name, 

 it does not always compare in beauty with many of the other 

 frogs of North America. It seldom has the richness of colouring 

 that may be possessed by Rana drayionii, its neighbour on the 

 Pacific Slope. 



Rana aurora is easily confused with Rana drayionii (Fig. 251 

 and Colour Plate XV), because of the likeness, both in colouring 

 and proportions. The former frog can be distinguished by the 

 following characteristics: It has a longer leg, the greater length 

 especially noticeable in the tibia. Its skin is very smooth, 

 while that of Rana drayionii, especially in the full-grown frogs, 

 is always tubercular, and may be extremely so (even on the ear). 

 Rana aurora has a longer foot with a broader web, but with a 

 much smaller inner sole tubercle. 



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