THE FAMILIES AND GENERA OF BATS. 79 



KEY TO THE FAMILIES OK M1CROCHIROPTERA. 



Premaxillaries absent Meuadermiiwe, p. 101. 



Premaxillaries present. 



Premaxillaries usually free, always incomplete, their boundaries never 

 obliterated. 



Premaxillaries represented by nasal branch only, or with a very 

 incomplete palatal branch. 

 Postorbital processes absent ; second finger with two pha- 

 langes Rhinopomims, p. 80. 



Postorbital processes present; second finger without pha- 

 langes Emballonuriwe, p. 82. 



Premaxillaries represented by palatal branch only. 



Toes with two phalanges each ; pelvis with postacetabular 



foramen Hipposidehim:, p. 109. 



Toes (except hallux) with three phalanges each; pelvis with- 

 out postacetabular foramen. 



Premaxillaries bony throughout, in contact with each other 

 and with maxillaries ; tragus present ; fibula absent, 



Nycterim:, p. 99. 

 Premaxillaries partly cartilaginous, free from each other 

 and from maxillaries ; tragus absent ; fibula present, 



Rhinolophim;, p. 100. 

 Premaxillaries always fused with surrounding parts, complete or- incom- 

 plete, their boundaries very early obliterated. 



Ischia fused together beneath posterior extremity of sacrum, 



Noctilionid.e, p. 95. 

 Ischia not fused together beneath sacrum. 



Fibula robust (its diameter usually about half that of tibia), 

 contributing largely to strength of short, stout leg. 

 Third phalanx of middle finger cartilaginous except at 



extreme base; claws simple MoLossioas, p. 241. 



Third phalanx of middle finger bony ; claws with basal 



talon Mystacopid^e, p. 239. 



Fibula very slender or rudimentary, not contributing essen- 

 tially to strength of long, slender leg. 



Third phalanx of middle finger cartilaginous except at 

 extreme base. 



Humerus with trochiter much longer than trochin, 

 projecting conspicuously beyond head, and forming 

 a complete secondary articulation with scapula, 



Vespertilionims, p. .195. 

 Humerus with trochiter scarcely longer than trochin, 

 not projecting conspicuously beyond head, its articu- 

 lation with scapula frequently slight or none. 

 Presternum not broadened anteriorly ; keel of 

 * mesosternum very high ; claw of thumb well 



developed Natalim:, p. 180. 



Presternum greatly broadened anteriorly ; keel of 

 mesosternum a mere ridge ; claw of thumb rudi-' 



mentary Furipteeim;, p. 186. 



Third phalanx of middle finger bony. 



Canine teeth very large, shearlike ; molars enormously 

 reduced, without trace of crushing surface, 



Desmouontid^e, p. 176. 



