78 
BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
less developed. Middle upper premolar (pm 3 ) large, almost equal 
to the canine, with well developed inner and posterior secondary 
cusps. It is closety resembled by pm 3 , the main cusp of which 
is, however, more slender. The last premolar both above and below 
has a distinct inner and posterior secondary cusp and a bifid main 
cusp. First lower molar of the same type, but shorter. Second 
and third molars both above and below much shorter than the 
other teeth when viewed from the side, each with three outer and 
three inner cusps between which extends the fairly well-defined 
median groove. Skull not unlike that of Pteropus in general form, 
but occipital region apparently not tubular. The deflection of the 
occiput is so slight that the alveolar line when projected backward 
passes through base of zygoma. Externally characterized by unusu- 
ally short legs, absence of tail, presence of claw on index finger, and 
attachment of wings low on sides of body. 
Species examined. — Harpyionycteris whiteheadi Thomas. 
Suborder MICROCHIROPTERA. 
1821. Insectivora Gray, London Medical Repository, XV, p. 299. April, 1, 
1821. 
1872. Animalivora Gill, Arrangement of the Families of Mammals, p. 16. 
November, 1872. 
1875. Mmrochiroptera Dobson, Ann. and Mag. Nat. Hist., 4th ser., XVI, 
p. 346. November, 1875. 
1878. Microchiroptera Dobson, Catal. Chiropt. Brit. Mus., p. 2. 
1899! Microchiroptera Matschie, Flederm. des Berliner Mus. ftir Naturk, 
p. 1. 
Geographic distribution. — The same as that of the order Chirop- 
tera (p. 43) . 
Characters. — The following characters may be enumerated in addi- 
tion to those mentioned in the key on page 43 : Tragus normally 
present (absent in Rhinolophidse and Hipposideridse only) ; skull 
with rostral portion usually specialized in form ; postorbital proc- 
esses usually absent or rudimentary (well developed in Emballonu- 
ridse) ; teeth of the insectivorous type, except in some of the Phyllos- 
lomidse and in the Desmodontidse, the cheek teeth of the upper and 
lower jaws very different from each other (except in the Desmodon- 
tidse) , the cusps of the molars when present homologous with those 
of the primitive tuberculo-sectorial tooth ; lower incisors often 3-3. 
* Xumber of forms. — By far the greater number of known bats are 
members of the suborder Microchiroptera. At least 600 forms are 
now recognized. 
Principal subdivisions. — As might be expected from the large num- 
ber of its species, the suborder Microchiroptera presents much more 
diversity of structure than the Megachiroptera. The genera group 
themselves naturally into 16 families. 
