1914.] 



REITHKODONTOMYS MEGALOTIS GROUP. 



31 



Distribution. — Greater part of Kansas, Nebraska, Iowa, Missouri, 

 and South Dakota; southern North Dakota; southeastern Montana; 

 eastern Colorado and eastern Wyoming. 



Characters. — Similar to megalotis, but black of upperparts more 

 extensive and ochraceous shades more intense; ears slightly smaller; 

 tail shorter. 



Color. — FuU winter felage (topo types): Upperparts mixed black 

 and light ochraceous-buff ; in some specimens the median dorsal area 

 is noticeably darker, in others the color is nearly uniform over the 

 whole back; sides clear buff, the lateral line sometimes, though not 

 always, well-marked; ears hair-brown externally, thinly clothed with 

 buffy hairs on inner surface, and with a tuft of ochraceous-buff hairs 

 at anterior base; feet and underparts white; tail sharply bicolor, 

 dark hair-brown above, white beneath. 



STcuU. — About same size as that of megalotis (smaller than that of 

 aztecus) ; rostrum shorter and broader. 



Measurements.^ — Type: Total length, 133; tail vertebrae, 52; hind 

 foot, 15.5. Average of 6 nearly adult specimens from eastern 

 Nebraska (Neligh and Verdigris): Total length, 135 (130-142); tail 

 vertebrse, 61 (57-65); hind foot, 17.5 (16.5-18); ear from notch, 10. 5 

 (10.3-11.1). Average of 8 adults from Kennedy, Nebr.: 133; 63; 

 17.5; 10.8. Skull: (See table, p. 81). 



Remarlcs. — ^This form clearly belongs in the megalotis group and 

 apparently intergrades with aztecus, as indicated by specimens from 

 central Colorado (Loveland, Greeley, and Canon City). These aver- 

 age slightly paler and grayer than the typical form and their skulls are 

 intermediate in size, with somewhat longer rostri than in typical 

 dycJiei. 



The series from Kennedy, Nebr., on which Dr. Allen based the sub- 

 species ^'nelrascensis" seem to be indistinguishable from specimens 

 of typical dycliei in comparable pelage. At many localities in 

 Nebraska and Kansas R. albescens griseus occurs with the present 

 species, and although occasional specimens are hard to distinguish by 

 color alone, yet in size and cranial characters the species are distinct. 

 Dr. Allen confused the two in his original description of dycliei, the 

 series listed from. Onaga, Kans., and London, Nebr., being referable 

 to griseus. The latter race may be distinguished from dycliei by its 

 smaller size, shorter tail, and smaller skull with short rostrum and 

 short palatal foramina. In coloration dycliei is more intensely ochra- 

 ceous than griseus and often not conspicuously darkened on the dorsal 

 area; griseus is distinctly grayer and the ochraceous-buff of the sides 

 is paler and less extensive. 



1 The great variation in the measurements of this species given by Dr. Allen in the original description 

 indicates that probably many of the specimens were immature and the average therefore too small. 



