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roosts at night. In such resorts: which are Srainanity used 
during summer as sleeping places during the day, immense © 
quantities of guano are deposited which become valuable. as 
nitre supplies. Thus the insignificant bat plays no insignifi- — 
cant part in the warlike preparations of militant nations, as 
the nitre so secured is an essential factor in gunpowder. — 
During hibernation and daily sleep, bats are in danger from ~ 
prowling animals which creep upon them when at rest; while — 
during their hawking excursions after insects they frequently is 
fall victim to the nocturnal birds of prey. Sth 
Bats may be reckoned among the beneficial animals, as their _ 
food consists almost exclusively of insects in temperate regions. es 
They are aptly compared to swallows, as their benevolent in- _ 
tent and their graceful motions are both similar. The bats of 
the tropics are larger and do not content themselves with in- — ie 
sects and other small arthropods. Various fruits form a wel- 
come contingent, if not the staple of the diet, while still others f J i - 
are bloodthirsty enemies of large animals which they attack — 
stealthily, sucking the blood painlessly and escape unperceived. © it 
The hair of bats may be distinguished from that of other 
mammals by its peculiar microscopical structure. Thefine fur — 
is a refuge for many parasites of various sorts. It remains to 
mention the anatomical peculiarities of the group. 
The dentition is extremely variable, but in general resembles : 
that of the Insectivora. The greatest diversities are found a 
between the frugivorous and insectivorous bats. The number — 
of teeth varies from 24 to 38. The statements of various auth- — 
ors vary greatly as tothe number of teeth—a fact caused by 
their deciduous character, particularly of the incisors and pre- 
molars. The molars have two or three points which are vari- ty 
ously arranged and those of opposite teeth fit between each 
other. The incisors are small and above are often arranged 
in oblique series not meeting in the median line. The milk 
dentition is quite different from the permanent. 
Most species produce but a single young at a birth or at most 
two. The mother hangs by the thumbs, it is said, and the 
young are dropped into a pocket formed by the incurved tail with 
the membranes attached. Here they remain clinging for a day 
to peculiar processes between the thighs,or at once clamber up 
to the two pectoral mammz. Although northern species mate — 
ordinarily in Autumn, eggs are not fertilized until Spring, 
when impregnation takes place. The placenta is disc-like any 
, the uterus has two cornua. The penis is pendulous. 

