i I INTRODUCTION. 



fingers, on the chin, the belly, and on the free 

 edge of the web between the toes (Fig. 27, a). 



Discoglossus. 



On the inner side of the three inner fingers and 



the antebrachium, and on the third, the second 



and third, or the second, third, and fourth toes 



(Fig. 27, c) . . Bombinator pachypus. 



On the inner side of the two inner fingers and the 



antebrachium . . Bombinator igneus. 



On the inner side of the three inner fingers 



(Fig. 27, d) Bufo. 



On the inner and upper side of the inner finger 

 (Fig. 27, e) . . . . Rana. 



At the base of the inner finger . . Hyla. 



It sometimes happens that old females present at 

 least traces of these organs, the appanage of the males. 

 I have recorded such a case in a Rana temporaria with 

 eggs in the oviducts ; Bosca has found the same 

 anomaly in a Pelodytes punctatus, and Mehely in five 

 specimens of Bombinator pachypus. These horny 

 productions are usually dark brown or black ; they 

 are greyish in Rana esculenta and agilis, colourless 

 in Hyla arborea. Their aspect under the microscope, 

 and the differences they present according to the 

 species, have been studied by Lataste, who has shown 

 that they are low and obtuse in Rana esculenta and 

 agilis, erect and pointed in Rana temporaria and arvalis 

 and Discoglossus, pointed and oblique or hooked in 

 Bombinator and Pelodytes, pointed, erect, and crenu- 

 lated in Bufo vulgaris and viridis, and obtuse and 

 crenulated in Bufo calamita (Fig. 28). 



As in all Batrachians in which no courtship takes 

 place, the males are not distinguished by any orna- 

 mental appendages or more vivid colours, but in Rana 

 temporaria and arvalis they acquire during the pairing- 

 season a peculiar swelling of the skin, by which the 

 back, and especially the gular region, take on a bluish 

 tinge and a flabby texture, strongly contrasting with 

 the aspect of the same parts later in the year. The 



