PAIRING AND OVIPOSITION. 65 



Even iu this category there are occasional excep- 

 tions. Such are the cases recorded by Martin and 

 Rollinat and W. Evans, of single couples of the 

 common toad found breeding near Argenton, in 

 France, on the 18th June, and near Edinburgh on 

 the 13th June, two or three months after the other 

 individuals in the same localities had deposited their 

 spawn and left the water. These exceptional cases 

 are probably due to some accident having prevented 

 the female from resorting to the breeding-place at 

 the proper time. Males, we know, may long retain 

 their genital ardour, so many of them, owing to their 

 excess in numbers, being unable to find a mate. 



"We next find species which may also be said to 

 have a short breeding season, but which do not con- 

 gregate with the same ensemble, the condition of the 

 genital products not being the same at a given time 

 in all the individuals. In these species the female 

 does not, as a rule, enter the water until ready to 

 spawn, and the embrace is, in consequence, of short 

 duration, often taking place only at night. To this 

 category belong Pelobates, Pelodytes, Hyla, and Rana 

 agilis. The males are not, as a rule, animated with 

 the same frenzy as we observe in the first type, and 

 will often let go the females when disturbed or 

 handled. 



A third category is represented by Bufo calamita, 

 Bufo viridis, and Rana esculenta, which spawn but 

 once a year, but the breeding season of which extends 

 over a longer period, viz. two or three months, within 

 the same district, with an ultimum mostly depending 

 on the weather. 



Lastly, all the species of the family Discoglossidse, 

 and apparently also some individuals of Pelodytes, are 

 able to breed twice or more every year. Bombinator 

 spawns first in spring and again in summer, some- 

 times as late as August or the beginning of September ; 

 Discoglossus and Alytes as often as three or four times 

 at distant intervals during the warmer months, the 



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