MAMMALS OP THE MEXICAlf BOUNDARY. 



463 



paler, dusty, grayish color and in having more hairy tails, the hairs 

 concealing the caudal annuli. Those from the Colorado River are 

 almost as pale, but have a more yellowish coloring. An extreme 

 specimen (Cat. No. 60157, U.S.N.M.), from the Colorado at Monu- 

 ment No. 204, is of a yellowish rust-color, almost exactly intermediate 

 in coloration between the type of R. megalotis deserti and a specimen 

 of the R. mexicanus group from Mazatlan, Mexico, and suggests an 

 affinity between the R. mexicanus and R. megalotis groups. 



Habits and local distribution. ^-In. March, 1894, we found the desert 

 harvest-mouse abundant along the Colorado Eiver from Yuma to the 

 Gulf of California. Its favorite home was amongst the dense growth 

 of arrowwood that covers so large an extent of the Colorado bottom 

 lands. On the Colorado Desert a few were taken at Seven Wells and 

 Gardners Laguna, on the Salton River, in Ivower California, in April, 

 1894. Females taken April 15 and 20, 1894, would have given birth 

 to 4 young each. 



Record and measurements of 39 specimens of Reithrodontomys megalotis deserti. 



Locality. 



Sex and 

 age. 



Monument No. 204, on bank of 

 Colorado River. 



do '. 



do 



do 



do 



Monument No. 205, on bank of 

 Colorado Uiver. 



do 



do 



....do 



....do 



....do ^ 



...do 



....do 



...-do 



....do 



...do 



....do 



....do 



....do 



...'.do 



....do 



....do 



....do 



....do 



....do 



....do 



....do -.... 



...do 



1894. 

 Mar. 15 



Mar. 16 

 Mar. 17 

 Mar. 26 

 ...do.. 

 Mar. 26 



...do.. 

 ...do.. 

 ...do... 

 ..-do.-. 

 Mar. 27 

 ...do... 

 ...do... 

 .--do... 

 ...do... 

 Mar. 28 

 ...do-.. 

 ...do... 

 ...do--. 

 Mar. 29 

 Mar. 30 

 ...do... 

 ...do... 

 ...do... 

 ...do... 

 ...do... 

 ...do... 

 ...do... 



?ad. 



cfad. 

 Jim. 

 (fad. 

 9 ad. 

 cTad. 



S juv. 



9 



9 jav. 



9 



9 ad. 



9 



J ad. 



cf 



cT 



cf ad. 



d 



cf ad. 

 9 ad. 



9 ad. 

 9 im. 

 (f ad. 



cf 

 S 



mm. 

 121 



139 

 132 

 131 

 151 

 140 



116 

 117 

 127 

 120 

 128 

 118 

 146 

 138 

 131 

 142 

 136 

 131 

 128 



ram. 

 66 



76 

 63 

 71 

 78 

 71 



60 

 59 

 66 

 62 

 68 

 61 

 80 

 79 

 73 

 75 

 74 

 73 

 66 



Ttllfl. 

 17.0 



18.0 

 17.0 

 17.0 

 17.0 

 18.0 



16.0 

 16.0 

 17.0 

 17.0 

 17.0 

 16.5 

 19.0 

 18.6 

 17.0 



lao 



18.0 

 17.0 

 17.0 



144 

 136 

 124 

 124 

 143 

 126 

 137 

 119 



18.0 

 17.6 

 17.0 



mm. 

 10.5 



11.0 

 11.0 

 11.0 

 11.0 

 12.0 



11.0 

 11.0 

 10.0 

 11.5 

 11.5 

 11.0 

 12.0 

 11.0 

 11.0 

 11.0 

 10.6 

 11.0 

 11.6 



12.0 

 12.0 

 10.5 



18.0 

 16.5 

 18.0 

 17.0 



12.0 

 10.5 

 11.0 

 11.0 



