Jumping-mouse 593 



says*" that in Illinois this species'* produces only from 2 to 4 

 young at a birth, and * * * probably not over i or 2 litters 

 in a year." E. Slade of Somerset, Mass., writes Dr. C. H. 

 Merriam: "As a rule, 3 litters are produced in a season, 

 each consisting of 2 to 4 young." Audubon and Bachman 

 make a similar statement,*^ so that the northern animal appears 

 to have larger broods, though it is likely that the southern one 

 breeds twice as often each season as the species observed by 

 Preble near Hudson's Bay. 



In Massachusetts this same observer found evidence that young 

 the young are born in May or June, but sometimes as late as 

 September, "from which it seems probable that a second litter 

 is raised, or that the breeding season continues throughout 

 the summer. Three specimens obtained by my brother at 

 Wilmington, Mass., September 25, 1897, which, with their 

 parents, were turned up by a plow, were so young [about two- 

 thirds grown] that the posterior upper molars had just ap- 

 peared" (loc. cit., p. 8). Similarly Audubon and Bachman 

 state :*^ "We have seen the young on several occasions in 

 May and August." 



The mother frequently carries them attached to her teats. 

 Dekay records "^ a case of a female going off with 4 young ones 

 attached to their mother by her teats; and many observers 

 since have added similar testimony. This habit is well- 

 developed in most of the Mice, but it is most remarkable in 

 the Zapus, because of the flying leaps that it takes. It is hard 

 to say which gets the worst of it, in these vast bounds, the 

 helpless sucklings, bumped and bruised on brush and stones, 

 or the mother who is trying to make unusual speed with three 

 or four heavy babies hanging to her flesh like a bunch of little 

 bull-dogs. 



A popular error has already grown up around this fact, an 



'" Quad. 111., 1857, p. 97. " Mam. Adir., 1884, p. 292. 



" Quad. N. A., 1849, Vol. II., p. 254. " Ibid. 



" Zool. N. Y., Pt. I, p. 72. 



