INTBODCCTI'.'N. 



are less developed than in It. exculenta, so that the free borders 

 appear more cresoentie. The supplemental toe forms only a 

 soft and inconspicuous prominence. The back is mostly smooth ; 

 the raised glandular ridge, which extends along each side from 

 the eye to the thigh, is present, but is much narrower and less 

 prominent than in R. esculenta ; another ridge passes from the 

 angle of the mouth to the shoulder. The colouring in general, and 

 especially the ground colour of the dorsal surface, varies from the 

 brightest tints to the darkest brown-black ; the conditions causing 

 these variations being, no doubt, the same as those described above 

 in K. esculenta. A dark-brown specimen taken from a dark frog- 

 tank is usually yellowish red on the following day. The black 

 patch between the angle of the mouth and the shoulder has 

 given this species the name of R. temporaria, and is constant. A 

 black stripe passes from the eye across the nostril to the tip of 

 the snout, and a similar one is found upon the anterior surface 

 of the upper arm. On the hind legs the bands are chiefly trans- 

 verse. The ventral surface is yellowish, and sometimes spotted. 

 The thighs have a granular appearance, and these as well as the 

 belly and the neighbourhood of the anus have frequently a reddish 

 coloration presenting the appearance of an irritated surface. 



Rana oxyrhinus, Steenstrup. This species is always smaller and 

 more elegant in shape than the preceding one. The head is conical, 

 with the pointed snout projecting beyond the lower jaw; a feature 

 which is especially evident on looking from below. The space be- 

 tween the eyes is narrower than in R. temporaria, and is not 

 grooved, but convex; the fronto-parietal bones are narrow and 

 arched. With respect to the arrangement of the vomerine teeth 

 and the sizes of the apertures of the Eustachian tubes, this species 

 holds an intermediate position between the other two. Next to 

 the pointed snout, the greatest difference between this species and 

 R. temporaria is the presence of a much larger supplemental toe, 

 which is of cartilaginous hardness, compressed from side to side, 

 and contains a larger bone *. The vocal sacs are absent. In the 

 males the web of the longest toe reaches to the last phalanx but 

 one ; in the females, on the contrary, the last three phalanges pro- 

 ject freely beyond the web. The extremities of the toes are more 

 pointed than in R. temporaria, in which respect, as also in several 



1 According to Steenstrnp, 1. c., the size of the supplemental toe is in R. temporaria 

 one-half and in S. oxyrhinus two-thirds of that of the next toe. 



