44 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



Remarks. — The distinction between these two groups is so sharp 

 and definite that it is a matter of great convenience to recognize the 

 Megachiroptera and Microchiroptera as suborders, though it may be. 

 questioned whether they are of equal structural importance with 

 other suborders of Mammalia. 



Suborder MEGACHIROPTERA. 



1821. Frnctivorw Gray, London Medical Repository, XV, p. 299, April 1,-, 

 1821. 



1872. Frugivora Gill, Arrangement of the Families of Mammals, p. 18, No- 

 vember, 1872. 



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

 340, November, 1875. 



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



1899. Megachiroptera Matschie, Flederm. des Berliner Mus. fur Naturk., 

 p.l. 



Geographic distribution. — Tropical and subtropical regions of the 

 Old World, east to Australia, Samoa, and the Caroline Islands. 



Characters. — In addition to the characters given in the key (p. 43) 

 the following may be mentioned: Tragus never present; skull with 

 rostral portion variable in length, but never specialized in form ; pre- 

 maxillary well developed, usually free, always without palatal branch ; 

 postorbital processes well developed; teeth very highly modified for 

 frugivorism, the cheek teeth of upper and lower jaws closely resem- 

 bling each other in form; molars normally with two blunt cusps on 

 anterior portion of crown, these representing the protocone and para- 

 cone in upper teeth, the protoconid and metaconid in lower; mandi- 

 bular incisors never more than 2-2. 



Number of forms. — According to Matschie about 150 recognizable 

 forms of Megachiroptera are now known. 



Principal subdivisions. — The Megachiroptera are all members of 

 one family, the Pteropidse. 



Remarks. — Though the structure of the teeth presents a high de- 

 gree of specialization, the development of the wings and the form of 

 the skull represent an evolutionary stage much nearer to normal mam- 

 mals than that which has been reached by the Microchiroptera. The 

 index finger retains its ungual phalanx and much of its primitive in- 

 dependence from the third digit; the humerus has not yet developed 

 a high, flange-like deltoid crest for muscular attachment, nor has it 

 acquired a secondary articulation with the scapula. Finally the 

 whole general appearance of the skull is more nearly that of an ordi- 

 nary mammal and less distinctively that of a bat. On the other hand, 

 the molar teeth have nearly lost all distinct traces of their primitive 

 structure. That this fact is of relatively little importance is shown, 

 however, by the existence in a family of Microchiroptera, the Phyl- 

 lostomidse, of a complete series of stages connecting the normal form 



