1911] Taylor: MammaU of the 1909 Nevada Expedition. 243 



Eighteen of the series are males, fifteen females. Seven of the 

 males secured presented greatly developed testes. These were, 

 respectively: no. 8186, May 17; no. 8199, May 20; no. 8201, IMay 

 21; nos. 820i) and 8210, June 16; no. 8213, July 26; and no. 

 8214, August 4. Four of the females contained developing 

 embryos. These were: no. 8192, ^lay 18, 5 emI)ryos; no. 8196, 

 :\Iay 19, 4; no. 8204, May 25, 1; no. 8215, August 8, 3. One 

 female, no. 8207, secured ]\lay 31, was suckling young. Ap- 

 parently one pair pectoral, and two pairs abdominal mammae 

 were functional. Six specimens marked "juvenal" were col- 

 lected: no. 8197 2, May 19; no. 8198$, May 20; no 8203$, May 

 21 ; no. 8205 $, May 26 ; no. 8206 $, May 30 ; no. 8212 c^, June 20. 



It is evident that the period of gestation lasts for several 

 months, having begun before May 15 and continuing beyond 

 August 10. The seasons of gestation and suckling overlap very 

 markedly. Those living higher in the life-zone become sexually 

 active later than those on the desert tlat. The numbers of young, 

 too, according to our observations, vary to some extent. 



Neotoma nevadensis Taylor. 

 Nevada Wood Rat. 



Status. — Since the description of this species (Taylor, 1910, 

 p. 289) Dr. C. Hart Merriam has very kindly sent me four wood 

 rat skulls from northern Nevada which are probably referable to 

 it, and in the light of whose characters certain emendations must 

 be made in the diagnosis of the species, especially as regards size 

 of cranium. The four skulls are nos. 78283 c^, 78284$, and 

 78287 $, all from Deep Hole, southern end of Granite Range, near 

 Smoke Creek Desert, Washoe County, and no. 78289 $ from 

 Granite Creek in the same range of mountains. These localities 

 are approximately seventy miles to the south and a little to the 

 west of the type locality of nevadensis. 



The four skulls from the Biological Survey collection evi- 

 dently belong to older adults than any of our series, and are 

 shaped precisely as stated for nevadensis in the original descrip- 

 tion. These skulls are slightly larger in all proportions than 

 our series of desertoruni, and so very definitely larger than the 



