NYCTINOMUS .^GYPTIACUS. 
153 
his description of the species that there were two upper and four lower incisors, his 
drawing of the skull showed the presence of six lower incisors. Temminck’s 
explanation of these seeming discrepancies was that Geotfroy’s figure had been taken 
from the skull of a very young subject provided with six lower incisors, whereas 
the specimen he had examined was of more advanced age, and had been furnished 
with four incisors ; and he held that if Geofifoy had examined a greater number of 
individuals he might have met with others in \rhich a second pair of incisors had been 
lost, thus giving rise to the formula and that if he had met with still older 
individuals he might have found that the lower incisors had been entirely lost. 
Temminck received from Cretzschmar a Nyctinomus sent from Egypt by Rtippell. 
He recognized it to be an example of N. wgyptiacus, E. Geoffr. St.-Hil., in a complete 
state of development of the incisors—that is to say, with the talon of the canines very 
strong, the canines little separated, and only two lower incisors pushed in advance of 
this talon. 
He pointed out that this feature in the dentition of N. cegyptiacus was not confined 
to it, but that other species of the genus of the Old and the New Worlds had two, four, 
and six incisors in the lower jaw—the first presenting all the characters of fully-grown 
individuals, the last very often offering indications of youth, although externally it 
might be difficult to distinguish them at first glance from adults; and he held that it 
would be necessary to examine a very large number of individuals of all ages in order 
to establish a fixed rule as to the characters of the dentition of Chiroptera, and of the 
species of Nyctinomus in particular. To subject this group to the rule adopted generally 
in the case of mammals, and to classify them generically according to the number and 
the form of their teeth, appeared to Temminck, after very numerous observations, to he 
very hazardous. 
Dobson accepted Peters’s subdivision of Nyctinomus into two subgenera, Nyctinomus 
and Mormoiyterus. In the first of these he allocated N. africanus, ceston% cegyptiacus, 
tragatus, g)licatus, and fourteen other species, one of the leading features of this group 
being that the members of it are provided with | premolars. N. cegyptiacus, the 
type of the genus Nyctinomus, was, however, provided with only | premolars. On 
the other hand, Peters’s subgenus Mormoptems had assigned to it the same number of 
9 
premolars as Geofifoy said existed in Nyctinomus ; it had, moreover, ^ incisors, the 
number of these teeth represented in Geoffrey’s figure of N. cegyptiacus, which, 
according to the latter author, had united ears, but which Temminck and Dobson 
described as having had separate ears, one of the features of Mormopterus ! 
The genus Ninops, Savi had the exact dentition assigned by Dobson to his 
1 Nuoy. Giorn. di Letter, n. 21, 1825, p. 230 ; Bull. Sc. Nat., Juillet 1826, p. 386. 
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