Ranidae 



short, flat body is completely covered with small warts, from 

 the tip of the nose to the ends of the feet, producing a surface 

 that at first glance has somewhat the appearance of coarse sand- 

 paper. The frog is usually olive, grey, or yellow-brown, obscurely 

 spotted on the back (Colour Plate II), but often the whole 

 tubercular upper surface is bright brick-red. This red is some- 

 times to be seen on the lateral folds and on the tibia, when the 

 frog is brown or olive elsewhere. 



Rana boylii is excessively shy and wild. Its first instinct 

 is to hide. It scuttles head-first under cover at any approach. 

 If there is no place of concealment, or if its hiding place is dis- 

 turbed, it leaps great distances, and the enemy who can capture 

 it must be alert of sight and grasp. This frog emits a curious, 

 oily odour, greatly like that given out by the California Toad, 

 Bujo balopbilus. 



It has great power to change its colour from dark to light, 

 appearing nearly black at one moment, and light reddish or 

 yellowish grey half an hour later. 



Rana boylii is one of the most distinct species of frogs in 

 North America. Within its own range, the yellow colour of 

 the underparts will suffice to distinguish it, since Rana dray- 

 tonii, Rana aurora, and Rana pretiosa, the other frogs of the 

 Pacific Slope, have red instead of yellow in the colouration. Com- 

 pared with all the frogs of North America, it is peculiar in the 

 tubercular character of the skin, though some specimens of 

 Rana draytonii approach it in this characteristic. Rana boylii 

 is like Rana pretiosa, Rana catesbiana, Rana grylio, and Rana 

 septentrionalis in the extensive webbing of the feet. 



RANA VIRGATIPES, COPE 



IDENTIFICATION CHARACTERISTICS 



Colour: Chocolate-brown or brownish olive, with four narrow 

 lengthwise stripes of bright golden brown. There are two of 

 these stripes on each side. One occupies the position usually 

 held by the lateral fold (i. e. from the posterior part of the eye 

 backward) ; the other lies below this, and extends along the middle 

 of the side. The lower stripe is continuous with a stripe of bright 

 golden brown extending from the shoulder forward along the 



222 



