THE FAMILIES AND GENERA OF BATS. 
213 
Genus MIMETILLUS Thomas. 
1905. Mimetillus Thomas, Proc. Zool. Soc. London, 1904, II, p. 188, April 
18, 1905. 
Type-species. — Vesperugo moloneyi Thomas. 
Geographic distribution. — Fernando Po. 
Number of forms. — The type species is the only form yet dis- 
covered. 
Characters. — Dentition and skull as in Tylonycteris , but sides of 
rostrum projecting sufficiently to conceal tooth rows when viewed 
from above ; antorbital foramina large and conspicuous, directed for- 
ward; inner upper incisor bifid though not specially modified in 
form; and upper canine without secondary cusp. Externally differ- 
ing from all known bats in the greatly reduced wing, the third 
finger not longer than head and body; fifth metacarpal not quite 
equal to forearm in length, third and fourth equal to each other and 
slightly longer than forearm; tragus very short and broad, the free 
portion measured from anterior base less than one-third length of 
posterior border and barely equal to width at middle. Other exter- 
nal characters not essentially different from those of Tylonycteris. 
Species examined. — Mimetillus moloneyi (Thomas). 
Remarks. — The reduction in the size of the wings in Mimetillus is 
so great that specimens appear at first sight to be immature or even 
embryonic. Nothing comparable to this is known in other bats, 
since all of those with narrow wings, such as Pterygistes , Lasiurus 
and its allies, and the Molossidse, have the third finger fully devel- 
oped or even exaggerated in length, so that the wing loses none of its 
power.® Here, however, the third finger shares in the general short- 
ening, and the efficiency of the wing is much impaired . * * * 6 
Genus PHILETOR Thomas. 
1902. Philetor Thomas, Ann. and Mag. Nat. Hist., 7th ser., IX, p. 220, 
March, 1902. 
Type-species. — Philetor rohui Thomas. 
Geographic distribution. — New Guinea. 
Number of forms. — Only the type species is yet known. 
Characters. — Dental formula and structure of teeth as in Eptesicus 
except that inner upper incisor is of the same lengthened, strongly 
two-pointed type as in Tylonycteris , the upper canine is similarly 
provided with a large secondary cusp, and the upper premolar is 
much crowded between canine and first molar, its width nearly three 
« That the Lasiuri are unusually strong of ' wing is shown by the fact that 
they alone have reached the Galapagos and Hawaiian Islands. The migratory 
habits of some of the species are well known. 
6 See Thomas, Ann. and Mag. Nat. Hist., 6th ser., VII, p. 528. June, 1891. 
