TlIK .IIIMIMN(; MIVM. 



527 



which tlicy consich'r peculiarly filled I'oi- lliemselves is Ihe hir^(i, 

 succulent roots of the alfalfa. 



Pocket gophers apparently breed })ut once a year, the young 

 being born in ^larch and A])ril. There are usually three or four 

 in a litter, but there may be as many as six. They are born in 

 a nest of fine grass placed in a lateral passage of the main burrow, 

 and do not reach maturity till the end of the summer, when they 

 begin to shift for themselves. 



Economic status. — In this State the pocket gophers are too rare 

 to do much harm. But in many localities farther west they have 

 caused serious losses to farmers, gardeners and fruit growers. They 

 can be caught in small steel traps placed in the bottom of their 

 tunnels, or in special gopher traps. The animals always close every 

 hole through Avhich light enters and a small opening near the trap 

 takes the place of bait. They can also be poisoned with strychnine 

 placed in potato or dried fruit and dropped through a small open- 

 ing into the tunnel. 



Family ZAPODIDAE. 



JUMPING MICE. 



Dipodidae Flower and Lydekker, Introduction to the Study of 

 Mammals, pp. 479-480, 1891. Miller and Rehn, Proc. Bost. 

 Soc. Nat. Hist., Vol. 30, p. 166. 

 Zapodidae Lyon, Proc. U. S. Nat. Mus., Vol. 23, pp. 659-668. 

 Hind feet much elongated ; metatarsal bones five in number and 

 separate (not united into a cannon bone) ; no cheek pouches; tail 

 very long. 



The family is not easily confused with any other American 

 rodents. The kangaroo rats, which resemble the jumping mice in 

 form and inhabit southwestern North America, are distinguished 

 by the presence of external cheek pouches like those of the pocket 

 gophers. This f amity is distinguished from some of the old world 

 jumping mice by a number of osteological characters. 



Genus Zapus Coues. 



Zapus Coues, Bull. U. S. Geol. Surv., Terr., Vol. I, 2d Ser., No. 5, 

 p. 253, 1875. Preble, N. Amer. Fauna, No. 15, 1899. 



Dental Formula.—l, C, Pm, ^J; M, 1^ = 18. 



Generic characters. — Upper incisors with grooves on their an- 

 terior faces ; deep orange' in color ; premolar small and cylindrical ; 

 molars with somewhat complicated and crowded folds of enamel. 



