ind of
cross relationship attaching them to the _Nycteridae_ on the one hand
and to the _Emballonuridae_ on the other. These bats, distinguished
from all other Microchiroptera by the presence of two phalanges in the
index finger and the long and slender tail projecting far beyond the
narrow interfemoral membrane, inhabit the subterranean tombs in Egypt
and deserted buildings generally from north-east Africa to Burma and
Sumatra.

Typical bats.

[Illustration: FIG. 16.--Skull of Mouse-tailed Bat (_Rhinopoma
microphyllum_). X2. (From Dobson.)]

The last group, according to the system adopted by Prof. Max Weber, is
that of the _Vespertilionidae_, which includes such typical bats as
the pipistrelle, the noctule, and the long-eared species. By Mr G.S.
Miller[1] the first section of the family--_Natalinae_--is regarded as
of family rank, while the last section, or _Molossinae_, is included
by Dr G.E. Dobson in the _Emballonuridae_, from the typical forms of
which its members differ widely in tail-structure. In this extended
sense the family, which has a cosmopolitan distribution, may be
defined as follows:--The nostrils are normal and without a nose-leaf.
The ethmoturbinal bones of the nasal chamber are involuted. The
palatine processes of the premaxillae do not form a suture. The ear is
mostly large, with a tragus. The middle finger (except in
_Thyroptera_) has two phalanges. The fibula is usually rudimentary.
The tail is long and does not perforate the interfemoral membrane. The
incisors are generally 2/3 or 1/2, but may be reduced to 1/1 in the
_Molossinae_.

In the first subfamily, _Natalinae_, which is exclusively tropical
American, the other upper incisors are separated from one another and
from the canines; palatine processes of the premaxillae are at least
partially developed; and the dental formula is _i._ 2/3, _c._ 1/1,
_p._ {2 or 3}/3, _m._ 3/3. In general appearance these bats recall the
more typical _Vespertilionidae_, although the form of the muzzle is
suggestive of the _Mormopsinae_ among the _Phyllostomatidae_. Again,
while the form of the skull is vespertilione, the relation of the
vomer to the front end of the premaxillae is of the phyllostomine
type. The molars and incisors are likewise vespertilione, whereas the
premolars are as distinctly phyllostomine. Finally, while the third,
or middle, finger normally has two phalange