154 
THE MAMMALS OE EGYPT. 
subgenus Nyctinomus, but differed in that respect from Nyctinomus, Geoffrey. It was 
characterized also as having united ears. It is evident, if the premolar dentition is 
reliable as a subgeneric character, that the N. cegyptiacus, Geoffroy, is not N. cestoni. 
The Bysopes rupeli% Temminck, was regarded by Dobson as a synonym of N. cestoni ; 
but Temminck explicitly stated that its ears were not united by their internal 
borders, but at the same time he considered it as nearly allied to N. cegyptiacus. 
This seems probable, because its dentition was seemingly y, j, g, which is exactly 
the dentition of N. cegyptiacus according to Geoffroy’s figure. Is it possible that the 
union or disunion of the ears falls under the variations to be looked for in this genus, 
12 , 
and that the variation of the premolars from 2 to 2 is of little significance % 
In view' of these discrepancies, it is extremely difficult to differentiate betw'een 
N. cestoni and N. cegyptiacus, and I believe the difficulty arose in attempting to 
separate w'hat are in reality only local races of one and the same species. 
[I cannot agree w'ith the views expressed above as to the possible identity of 
N. cegyptiacus and JSl. tceniotis {=N. cestoni), and the theory of the shedding of the 
incisors, expressed by Temminck, is in no way borne out by the facts elicited by an 
examination of the specimens at my disposal. I believe that when specimens of this 
larger species are rediscovered in Egypt they will turn out to be referable to a species, 
of which there are several specimens from Cape Colony in the British Museum, with 
four lower ‘incisors (the number given by Geoffroy in the description of the species), 
'fhis view was expressed by me in the ‘Annals and Magazine of Natural History,’ 
ser. 7, vol. vii. 1901, p. 37. The South-African specimens closely agree with Geoffroy's 
figure, and so differ from the southern European species, N. tceniotis. As to the 
number of upper premolars, I believe tw'o will be found in all species of the genus ; 
but in some species the first is so exceedingly minute, that the aid of a strong lens is 
required to detect it even in a well-prepared skull. So that the presence of this tooth 
may have been easily overlooked. 
Dobson gave the following description of the type specimen of N. cegyptiacus 
preserved in the Paris Museum :— 
“ Much smaller than A. africanus. Ears quite separate, but close together by the 
bases of their inner margins; outer and inner margins of the ear-conch evenly convex, 
forming almost an arc of a circle above; antitragus half-oval, separated by a deep 
notch posteriorly ; tragus broad and rounded off above. Lips W'ith vertical w'rinkles. 
No gular sac in male or female. 
“ Wing-membrane from the low'er part of the tibia near the ankle. Fur deep 
smoke-brown above, paler beneath. Wing-membrane on the upper surface is covered 
with fur as far as a line draw'n from the middle of the humerus to the knee ; beneath 
