NYCTEKIDiE AND MEGADEEMATID^. 
105 
The construction of the nasal apparatus, as has been seen, is perfectly distinct in 
the two families. The Nycteridse are further distinguished from the Megadermatidae 
by other structural modifications. The spinal column of the former difiers from that 
of the latter in being prolonged to the extremity of the interfemoral membrane, and 
the terminal vertebra is T-shaped; whereas although the interfemoral membrane of the 
Megadermatidae is quite as well developed as in the Nycteridae, the terminal caudal 
vertebrae are rudimentary, and consequently the interfemoral membrane is not traversed. 
There is also a marked structural modification of the skull; in the absence of ossified 
premaxillae the upper incisor teeth in the Megadermatidae are wanting, while both bones 
and teeth are present in the Nycteridae. The Nycteridae have only the metacarpal 
representing the second digit of the manus, whereas in the Megadermatidae a phalange 
is added. In the two families the fibula is absent. 
Dobson, in contrasting Megaderma with Nycteris, stated that the affinity of the two 
genera was shown by the peculiar form of the frontal bones, and also by the form and 
structure of the ears. The structure of the ear in these two bats is, however, 
perfectly distinct. In the Nycteridae the inner borders of the ears are never united 
(though the bases are connected by a low frontal band), and consequently the inner 
border, as it approaches the base, curves outwards and backwards into the cavity 
of the conch, and ends in its inner aspect immediately behind the origin of the tragus 
in a small lobular projection. In the Megadermatidae, owing to the union of the inner 
borders of the ears, this arrangement is entirely absent. In the lower portion of the 
external border of the ear of the Nycteridae there exists on the inner surface a 
thin fold of skin variously developed, but always markedly present, which passes 
downwards along the wall of the conch, and terminates slightly above the outer margin 
of the external meatus, from which it is separated by a thickened fold of skin that 
runs backwards to the wall of the conch. A more or less shallow depression is defined 
by the union of these two folds. The former of these folds is entirely unrepresented 
in the Megadermatidae, but there are slight indications of the existence of the latter. 
In the Nycteridae the external border of the ear before its attachment to the side of 
the head develops a well-marked sensory semicircular antitragus, a structure which is 
absent in the Megadermatidae in which true sensory hairs in this region of the ear do 
not occur. In the Nycteridae the inner and outer surfaces of the ear-conch and of the 
tragus are covered with circular areas, from the centre of each of which springs a 
sensory hair, but these structures are completely absent from the thin membranous 
tragus of the Megadermatidae. 
The foregoing structural differences seem of sufficient importance to entitle the 
animals which manifest them to be referred to two distinct families, viz., the Nycteridae 
and Megadermatidae, and hence they appear as such in these pages. 
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