ALLEN: MAMMALS FROM THE BLUE NILE VALLEY. Doo 
size, the skull is longer, with a larger rounder braincase, which is less 
markedly truncate at the lambdoid crest, in contrast to that of emint 
which is almost squarely truncate in posterior outline. In C. pumilus 
the lambdoid ridges are not transverse but are directed slightly for- 
ward so that they do not form the posterior boundary of the skull as 
in these two species, and the supraoccipital is not hidden by them in 
dorsal view. The skull of C. bivittatus (no. 14,456) measures: — 
greatest length 21 mm., palatal length 8.5, zygomatic breadth 12.5, 
width outside last molars 9.1, interorbital constriction 4.2, upper 
tooth row excluding incisors 7.5, lower tooth row excluding incisors 8. 
In one of the two specimens, the minute first upper premolar is 
nearly in the tooth row, but very slightly exterior to the posterior heel 
of the canine; in the other the same tooth is entirely external to the 
tooth row and placed in the external angle between the canine and the 
second premolar, which are actually in contact on each side. Some- 
| what similar variation has just been noted in case of C. emini, and is 
: evidently an expression of the tendency toward shortening the tooth 
row through the displacement and eventual loss of the minute first 
premolar. 
CHAEREPHON PUMILUS (Cretzschmar). 
Lesser Free-tailed Bat. 
Dysopes pumilus Cretzschmar, Riippell’s Atlas reise nérdlichen Afrika. 
Saugeth., 1826, p. 69, pl. 27, fig. a. 
El Garef and Magangani where they seemed to be common. They 
appeared shortly after dusk, flew rather high and swiftly. This 
_ Species is dichromatic and presents a russet and a blackish or dark 
| chocolate-brown phase. The former condition seems to be due to a 
lack of the blackish pigment in the hairs; the latter to the mixture of 
_ the reddish and the blackish pigments which commonly coexist in the 
| pelage. The extreme tips of the hairs are pale, giving a faintly hoary 
| aspect to the back. The lower surfaces are paler than the upper and 
along the sides of the body from the axilla to the groin is a pale, almost 
whitish band of fur on the wing-membranes, that contrasts with the 
darker sides of the body. These details of color have not heretofore 
P been described, no doubt because they are not very apparent in alco- 
holic specimens. The original description was based on a specimen 
from the Red Sea coast at Massowa, collected by Riippell. The 
| forearms of the five specimens obtained measure from 35.5 to 37.5 mm., 
| Several specimens of this bat were obtained along the Blue Nile at 
