60 
NATURAL HISTORY. [NEW BUILDING. 
from Vespertilio in the length of the legs and tail, and 
especially of the heel bones. Pachyotus differs from Sco- 
tophilus in interfemoral membrane being slightly, and 
Lasiurus in its being very hairy. 
The tribe of Bull Dog Bats ( Noctilionina ) have acutely 
tubercular grinders, and feed on insects, like the true 
Bats, but their wings are very long and narrow, their 
bodies thin, and their tails thick ; their lips are generally 
very thick and prominent, resembling in appearance those 
of a bull dog. They are divided into genera according 
to the position of the tail.—In many the tail is short, and 
the tip is produced on the upper surface of the large in¬ 
terfemoral membrane, which is folded inwards when the 
animal is at rest. The genus Mormops is peculiar for hav¬ 
ing a number of differently placed membranaceous ridges 
on the face and chin, giving the animal a most grotesque 
appearance. Chilonycteris has a few ridges on the chin, 
and a toothed ridge across the end of the nose. These 
two genera are only found in the West Indies and Cuba. 
The genus Taphozous , only found in Africa and India, 
has a simple face, with a large pit on the forehead; and 
the males have a transverse glandular slit on the throat. 
The Bull Dog Bat ( Noctilio ) of South America, has a 
very warty muzzle, with large dependent lips; they 
have only two cutting teeth in the lower jaw, which in¬ 
duced Linnaeus to separate this genus from the rest of 
the Bats, and to place it with the Rats ; the young ani¬ 
mals have a white streak on the back. The genus Pro - 
boscidea differs from the former in the head being long 
and conical, and the muzzle produced and sharp edged, 
and in having six cutting teeth below ; it is found only in 
Brazil; and Centronycteris only differs in the interfemoral 
membranes being conical and produced. In the genus 
Pteronotus the tail is elongated and produced to the end 
of the conical interfemoral membrane, as in the Vesper - 
tiiionina ; and the wings, as in some of the fruit-eating 
Bats, arise from the centre of the back, which is covered 
with fur on the side beneath them ; their chin is marked 
with membranaceous ridges. The third group consists of 
those genera which have the thick end of their tails pro¬ 
duced beyond the short transversely folded interfemoral 
membrane ; they have a large thumb, which is usually 
swollen beneath. The ears of Cheiromeles are small, and 
