4 ARKIV FÖR ZOOLOGI. BAND 2. N:0 20. 



the hind limbs, that ought to be in my opinion a very im 

 portant one, on account of which I am no longer in doubt 

 that Råna cequiplicata is a good distinct species. 



Its chief character is still the numerous irregularly placed 

 short dorsal folds, by which we are able, generally at the 

 first glance, to distinguish it from Ra7ia mascareniensis. If 

 the folds, as sometimes happens, are few and long as in E. 

 mascareniensis, there is, however, always one or another short 

 one, especially on the anterior part of the back, that is never 

 to be found in the latter. 



The other character, given by Boulenger, seems not to be 

 of so good a value, but on a strict examination it also pro- 

 ves quite constant, though there is a great variation in both 

 forms, on account of which, in this case, there are a great 

 deal of individuals connecting the species. 



On the 1st toe in R. cequiplicata the web reaches at least 

 the base of the distal phalanx biit sometimes över it; in R. 

 mascareniensis it usuaJly ends beyond that one, though it 

 may sometimes appear as a narrow fold as far as the last 

 joint. On the 2nd toe the web of the inner edge extends in 

 both species to the base of the penultimate phalanx, whereas 

 at the outer edge this toe in R. cequiplicata is webbed nearly 

 to the tip of the terminal phalanx but in R. mascareniensis 

 never farther than to its base and sometimes not so far. On 

 the 3rd toe we find in cequiplicata the web of the inner edge 

 reaching the penultimate joint, sometimes passing it some- 

 what, on the outer side out on the terminal phalanx but 

 sometimes only to its base, in R. mascareniensis the web al- 

 ways ends at the mentioned articulations, in its extremity 

 sometimes traced only as a very narrow fold. On the 4th 

 toe the web at both the edges in cequiplicata usually extends 

 to the middle of the penultimate phalanx, sometimes only 

 to the base of it, but sometimes also avS far as the distal 

 articulation, in mascareniensis, on the contrary, the two last 

 phalanges and sometimes also to some extent the third one 

 are free from web. On the 5th toe lastly the web in R. cequi- 

 plicata passes the distal articulation out on the terminal pha- 

 lanx, while in R. mascareniensis it never reaches över its base. 



A very good difference between the species is, as men- 

 tioned above, the different development of the hind limbs, 

 especially that of the foot, a character distinctly visible 



