382 THE ZOOLOGIST. 



down together from regions further to the north, the latter 

 pursuing the former, and that they never returned northwards by 

 the way they came (that is, down the eastern side of the Eocky 

 Mountains) ; but that the lynxes, having killed off all the rabbits, 

 crossed the range and returned northwards whence they came, 

 up the western side of the mountains. This belief, though 

 certainly baseless, sufficiently indicates the fully-recognised fact 

 of the simultaneous abundance of the two species, and the need 

 of some theory of more than ordinary plausibility to account, 

 firstly, for their extraordinary abundance, and, secondly, for their 

 subsequent simultaneous disappearance. 



The following cutting, from the 'Manitoba Free Press,' 

 confirms much that has been already said : — 



"This year [1887] an epidemic, which makes its appearance periodically, 

 is playing havoc with the wild rabbits of Manitoba. It is reported that the 

 dead animals are to be found lying in groups in their favourite haunts in 

 the bush. There is a strange feature connected with the epidemic which 

 afflicts them. When the rabbits become very numerous, the disease makes 

 its appearance, and soon the dead out-number the living. Indeed, in the 

 following year, scarcely a rabbit is to be found where before they were very 

 numerous. Then their numbers gradually increase until, at the end of 

 seven years' time, they swarm again as before the plague visited them. 

 The epidemic does not seem to extend its influence over the whole North- 

 West in the same year, but breaks out in different localities in successive 

 seasons. In each case, however, it appears from the evidence on hand, 

 that the seven years' cycle in each locality is fairly well defined. The 

 symptoms of the attack are about as follows : — the animal's throat swells, 

 diarrhoea sets in, and death follows." 



Messrs. Coues and Allen, in their 'Monograph of the Kodentia 

 of the United States' (U.S. Geological Survey Reports, 1877, 

 p. 371), remark that similar epidemics have been observed among 

 rodents, other than rabbits. Of the latter, one of the authors 

 writes : — 



11 Their decrease results usually from some not very obvious cause, 

 though sometimes supposed to be connected with a series of unusually 

 severe winters. That this is not the sole cause of their decrease, I have 

 been for a long time convinced ; but that it is due more to some prevalent 

 epidemic. Evidence of this is not generally easily obtainable, but proof of 

 it id other cases is quite abundant. In the case of the little Wood Hare, 

 Lepm xylvatious, I have repeatedly met with their dead bodies in the woods 



