vi RANINAE 263 



exceedingly timid, and to utter a short cry when disturbed and 

 making its enormous leaps. 



Another North American relation is E. halecina s. palustris, 

 frequenting the neighbourhood of ponds and rivers, very lively 

 and capable of jumping 8 to 10 feet. The tympanum is 



FIG. 50. Rana clamata, x|. 



smaller than the eye, but there is the same glandular lateral 

 fold as in K clamata. The vocal sacs are internal and decidedly 

 small. 



R. esculenta. The common Water-frog of nearly the whole 

 Palaearctic region is closely allied to the American Water-frogs 

 described above, and, like most of them, has the vomerine teeth 

 in two small oblique rows between the choanae and extending a 

 little beyond their posterior border. But the males have a pair 

 of external vocal sacs. The tympanum is distinct, about two- 

 thirds the size of the eye. The first finger is slightly longer 

 than the second. The toes are entirely webbed. Besides the 

 usual subarticular phalangeal tubercles, the sole of the foot is 

 provided with two metatarsal tubercles, the outer of which is very 

 small, while the inner is much larger, although varying in size 

 from a soft oval to a long, curved, shovel-shaped structure. The 

 skin is smooth, except for a pair of prominent glandular folds 

 which extend from behind the eye along the dorso-lateral line. 

 The coloration varies considerably. The upper parts are mostly 

 greenish brown, with black brown spots on the back, and larger 

 patches on the limbs. Most specimens have three lighter stripes 

 along the back, the middle one mostly green, the two lateral 

 bronzy brown and coinciding with the glandular folds. The 

 tympanum is brown, and there is occasionally a dark temporal 

 patch. The posterior aspect of the thighs is invariably 



