RANA. 291 



from the snout to above the vent, and the brown or 

 black spots often run together to form a dark stripe 

 on each side of the light one, and one or two others 

 on each side of the body. Contrary to a statement 

 made by Leydig in 1891, a light spot on the vertex, 

 corresponding to the frontal gland, may be very distinct, 

 as well marked as in any specimen of liana temporaria, 

 and much more than in R. esculenta and R. agilis. 



Lower parts white, often yellow near the groin, 

 immaculate, or the throat and breast spotted with 

 brown or greyish, or with red in the females ; in the 

 latter some red spots may be scattered on the belly. 



Males distinguished by a shorter body, much 

 stronger fore limbs, a large pad on the inner finger, 

 and a pair of internal vocal sacs. During the breeding- 

 season the pad on the inner finger, together with the 

 inner surface of the last phalanx, covered with black 

 horny spinules as in R. temporaria, and the skin like- 

 wise swollen with lymph, often assuming a uniform 

 pale blue or bluish colour on the upper surfaces and on 

 the throat. The web between the toes is then much 

 developed, with rectilinear or even convex outline, and 

 reaches the tips of the third and fifth toes. Females 

 during the breeding season develop pearl-like excres- 

 cences on the sides and limbs, which are, however, 

 less developed than in R. temporaria. 



The remarkable colour-dimorphism exhibited by this 

 species, an exact parallel of that observed in Disco- 

 glossus pictus, often occurs promiscuously, as, for 

 instance, near Berlin, where I have found the two 

 forms in nearly equal abundance in the same localities. 

 But this is not always the case, for Westhoff has 

 observed in Westphalia the striped form to be alone 

 present in certain bogs, whilst other drier stations 

 yield exclusively or principally the spotted form. The 

 latter is also the only one that has yet been found in 

 Norway, and is by far the more abundant in Denmark, 

 whilst in Sweden both seem to be about equally 

 represented. 



