NYCTINOMUS TENUIS* 
THE characters of this singular genus among the Vespertilionida?, were first 
defined by M. Geoffroy, in the Memoirs of Natural History, which form part of the 
description of Egypt, being the collection of observations which were made in that 
country during the Expedition of the French army. In proposing Nyctinomus as a 
genus, M. Geoffroy details the distinguishing characters in a copious manner, but with 
his usual perspicuity and elegance. In describing a new species from the Island of 
Java, it has appeared useful to me, to premise the substance of M, Geoffroy *s obser- 
vations, founded on a consideration of all the species previously known. 
M. Geoffroy commences by stating that no combination of characters departs 
farther from the common type of the Mammalia. The Nyctinomi, lie proceeds, 
have the flat nose and hanging lip of the mastiff, but in an excessive degree. 
The head appears as if crushed under the weight, and is in a great measure concealed 
by the amplitude of the ears. These are not simply vestibules to the auditory tube ; 
but they meet eacli other on the crown of the head, and, extending over the fore- 
head, are prolonged to the region of the intermaxillary bone, and by this arrange- 
ment they cover the cranium entirely. By their excessive development, and by 
means of a fold of the inferior lobe, they afford a peculiar protection to the eye : 
they apply themselves over this organ, and thus answer the purpose of a second 
eyelid. To keep the ears elevated, and to cause them, in one point of view, to 
constitute a concha before the meatus auditorius, and in another to afford to the 
eyes their proper axis of vision, requires the contraction of all the integuments of 
the head. The entrance of the ear is provided with that enlargement of the tragus 
which is peculiar to the Vespertilionidee, and which is termed by the French 
naturalists oreillon, and by Illigcr, the operculum. The cerebral case is broad and 
depressed, and the flatness of the head is not merely an appearance produced by the 
disposition of the ears, but it is real. The skull is abruptly truncated behind, and 
the foramen occipitale is remarkable on account of its excessive size. The nostrils 
would appear extremely simple, were it not on account of the upper lips, which 
are cleft, and passing backward, lose themselves on the cartilages of the nose, which 
have the form of a muff. The upper lips are wrinkled with from five to eight 
transverse folds on each side ; and they are rendered still more rugose by means of 
warts dispersed about them and about the ears. The olfactory openings are lateral 
and distant, they are at the same time circular, and in consequence of the thickness 
of the cartilage, they do not appear to possess the capacity of alternately opening 
and shutting themselves. This is, notwithstanding, the case with most of the other 
VespertilionidaB. 
M. Geoffroy proceeds to detail a remarkable peculiarity in this genus, by means 
