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BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
species, 80 genera, and Id families and subfamilies. As might have 
been anticipated, this work, the only complete special monograph of 
the order, was such a stimulus to the study of bats that since it 
appeared these animals have received more attention than ever before. 
In 1904 Trouessart recorded no less than 851 species, 122 genera, and 
18 families and subfamilies. It appears, however, that even these 
numbers are much too small. Detailed study of the skeleton, par- 
ticularly of the wing and shoulder girdle and of the structure of the 
tooth cusps, leads me to the conclusion that among the known species 
at least 173 genera and 36 families and subfamilies should be recog- 
nized. With regard to the species, recent work a shows that an enor- 
mous increase is to be expected as the characters on which distinc- 
tions are based come to be better understood. It seems highly prob- 
able that the total number of recognized bats will eventually exceed 
2,000 named forms. 
HISTORY. 
The following summaries are intended to give somewhat in detail 
the more important facts in the development of the classification of 
bats. The list, though incomplete, gives a sufficiently clear idea of 
the course that this work has followed. 
1758. Linnaeus, Systema Naturae, I, 10th ed. V espertilio, the only 
genus of bats recognized, appears as the fourth genus of Primates 
(p. 31.) The other genera are Homo , Simia , and Lemur. In the 
twelfth edition, 1766, Noetilio is separated from V espertilio and 
placed among the Glires. This is apparently the only instance of 
one genus of bats being referred to a different order from the others. 
1772. Briinnich, Zoologia Fundamenta. V espertilio is here one of 
the genera of Ferae ; the others are Hystrix , Lepus , Cavia , Castor , 
MuSy Sciurus , Erinaceus, Forex , Phoca , Lutra , Hyaena , Fells , Canis. 
C ereopitli.ecus , and I^emur. The orders recognized are: Bruta, Ferae, 
Pecora, Bellua, and Cetacea. 
1777. Scopoli, Introductio ad Historian! Naturalem. The genus 
V espertilio is placed between Brady pus and Lemur in the Ungui- 
culata. The position of this order in the system is as follows : 
Tribus Nil. Mammalia. 
Gens I. Cetacea. 
Gens II. Quadrupedia. 
Divisio I. Aquatilia. 
Divisio II. Terrestria. 
Ordo I. Ungulata. 
Ordo II. Unguiculata. 
a See especially the papers (Proc. Zool. Soc. London, 1905, II, pp. 75-145, 
October 17, 1905, and Ann. Mag. Nat. Hist., 7th ser., XVI, pp. 648-662, December, 
1905) by Mr. Knud Andersen on the Old World leaf-nosed groups. 
