Chap. XII.] AMPHIBIANS. 25 



With respect to sexual differences of color, Dr. Gun- 

 ther. knows of no striking instance with frogs or toads ; 

 yet he can often distinguish the male from the female, by 

 the tints of the former being a little more intense. Nor 

 does Dr. Gtinther know of any striking difference in ex- 

 ternal structure between the sexes, excepting the promi- 

 nences which become developed daring the breeding-sea- 

 son on the front-legs of the male, by which he is enabled 

 to hold the female. The Megalophrys montana* 1 (Fig. 

 32) offers the best case of a certain amount of structural 

 difference between the sexes ; for in the male the tip of the 

 nose and the eyelids are produced into triangular flaps of 

 skin, and there is a little black tubercle on the back — 

 characters which are absent, or only feebly developed, in 

 the females. It is surprising that frogs and toads should 

 not have acquired more strongly-marked sexual differ- 

 ences ; for, though cold-blooded, their passions are strong. 

 Dr. Gtinther informs me that he has several times found 

 an unfortunate female toad dead and smothered from hav- 

 ing been so closely embraced by three or four males. 



These animals, however, offer one interesting sexual 

 difference, namely, in the musical powers possessed by the 

 males ; but to speak of music, when applied to the discord- 

 ant and overwhelming sounds emitted by male bull-frogs 

 and some other species, seems, according to our taste, a 

 singularly inappropriate expression. Nevertheless certain 

 frogs sing in a decidedly pleasing manner. Near Rio de 

 Janeiro I used often to sit in the evening to listen to a 

 number of little Hylaa, which, perched on blades of grass 

 close to the water, sent forth sweet chirping notes in har- 

 monjfc. The various sounds are emitted chiefly by the 

 males during the breeding-season, as in the case of the 

 croaking of our common frog. 42 In accordance with this 



41 'The Reptiles of India,' by Dr. A. Gtinther, Ray Soc. 1864, p. 413. 



42 Cell, 'History of British Reptiles,' 1849, p. 93. 



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