THE FAMILIES AND GENERA OP BATS. 103 



KEY TO THE GENERA OF MEGADERMIMS. 



Upper premolars 2 - 2 ; interorbital region not conspicuously concave. 

 Lachrymal width much less than distance from orbit to canine, 



Megaderma, p. 103. 

 Lachrymal width greater than distance from orbit to canine, 



Lyroderma, p. 104. 

 Upper premolars 1 - 1 ; interorbital region conspicuously concave. 



Rudimentary premaxillaries rather distinct, projecting beyond line of 

 canines ; width of frontal expansion much less than distance be- 

 tween outer sides of toothrows Macroderma, p. 105. 



Rudimentary premaxillaries practically absent; width of frontal ex- 

 pansion about equal to distance between outer sides of toothrows. 



Upper molars with W pattern distinct Lavia, p. 105. 



Upper molars with W pattern distorted by reduction of the meso- 

 styles Cardioderma, p. 106. 



Genus MEGADERMA Geoffroy. 



1810. Megaderma Geoffeoy, Ann. Mus. Hist. Nat., Paris, XV, p. 197. 

 1866. Spasma Gray, Proc. Zool. Soc. London, p. 83. 



1878. Megaderma Dobson, Catal. Chiropt. Brit. Mus., p. 154 (part, sub- 

 genus). 

 1907. Megaderma Andersen and Wroughton, Ann. Mag. Nat. Hist., 7th 

 series, XIX, p. 130, February, 1907 (genus). 



Type-species. — Vespcrtilio spasma Linnaeus. 



Geographic distribution. — From India, Ceylon, and the Malay 

 Peninsula to Sumatra, Borneo, and the Philippine Islands. 



Number of forms. — Four forms are recognized by Andersen and 

 Wroughton. 



Characters. — Dental formula : 



.1.-2-4567 .0-0 l-l 2-2 3-3 OQ 



12-.1.-2-4567 ' * 2^2' C \=V* m 2^2' ™ S~3=^ 



Lower incisors large, indistinctly trifid, forming a continuous, 

 slightly convex row between canines, the inner tooth smaller than 

 outer. Canines large, with well-developed cingula, the lower with- 

 out secondary cusps, the upper with a minute anterior cingulum 

 cusp and a large posterior cusp at base of shaft. Anterior upper 

 premolar minute, on inner side of toothrow in angle between canine 

 and large premolar. First and second upper molars with three 

 main cusps rather close together, particularly in m 1 , and mesostyle 

 so reduced that the W pattern is considerably distorted by the partial 

 obliteration of the median commissures. Postero-internal heel well 

 developed but without trace of hypocone. Third upper molar with 

 four cusps and two commissures. Lower molars with cusps near 

 together and those on inner side reduced in size, particularly the 



