24 WALTER HEAPE. 



France (Beever, 1870), but it is not clear whether she is 

 monoestrous or polyoestrous ; when domesticated, however, 

 she is polyoestrous (Fleming, 1878; see also Aristotle). 



Certain wild sheep, 0. argali, O. burrhel, 0. poll, 

 have only one sexual season per annum, and are probably 

 monoestrous (Px-ejevalsky, 1876) ; whereas domesticated sheep 

 are polyoestrous, and may have such an extended series of 

 dioestrous cycles that they are capable of producing young 

 almost at any time of the year ; such^ for instance, are Dorset 

 Horns in the south of England and Hampshire Downs in 

 some parts of Ireland (compare also Aristotle). As a rule, 

 however, sheep in this country have a much more limited 

 polyoestrous season, — as, for instance, the Scotch black-faced 

 sheep, which has only two recurrent periods of oestrus 

 (Cameron, 1900). 



Variation in the periodicity of the sexual season of wild 

 animals, as compared with individuals of the same species 

 in captivity, has been noted in but few cases. Some of the 

 large carnivora in the Zoological Gardens exhibit great irre- 

 gularity in their sexual seasons, but too little attention has 

 been paid to the subject in these animals to allow of more 

 being said than that, in some cases, their generative activity 

 appears to have been stimulated, in others checked. 



The wolves in the Zoological Gardens have two sexual 

 sea5,ons, while the Tibet wolf (L. chanco) has only one (Pre- 

 jevalsky, 1876) in a wild state ; in New Mexico also, I am told 

 by a keen sportsman familiar with the country, wolves bear 

 young only once each year (W. Huston). The same is true 

 for the foxes in the Zoological Gardens; they have two sexual 

 seasons, while the Tibet fox (Prejevalsky, 1876) and the 

 English fox (Bell, 1874) have only one in the wild condition. 



The wild cat, on the other hand, in captivity does not 

 experience more sexual seasons than when in a feral state, 

 namely one (Hamilton, 1896) ; and the tame cat, when it 

 becomes wild, has apparently only one sexual season, whereas 

 the same animal under domestication has from two to four 

 sexual seasons per annum. 



