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 closely resembled by pm .., 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 Gkay, London Medical Repository, XV, p. 299. April, 1, 



1821. 

 1872. Animalivora Gill, Arrangement of the Families of Mammals, p. 16. 



November, 1872. 

 1875. Microchiroptera Dobson, Ann. and Mag. Nat. Hist., 4th ser., XVI, 



p. 340. November, 1875. 

 1878. Microchiroptera Dobson, Catal. Chiropt. Brit. Mus., p. 2. 

 1899. microchiroptera Matschie, Flederm. des Berliner Mus. fur 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- 

 ridae) ; teeth of the insectivorous type, except in some of the Phyllos- 

 lomidse and in the Desmodontidae, the cheek teeth of the upper and 

 lower jaws very different from each other (except in the Desmodon- 

 tidae), the cusps of the molars when present homologous with those 

 of the primitive tuberculo-sectorial tooth ; lower incisors often 3-3. 



Number 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. 



