THE FAMILIES AND GENERA OF BATS. 



115 



Characters. — Dentition essentially as in Hipposideros, except that 

 there is only one upper premolar and the upper canine has a large 

 secondary cusp rising to middle of posterior side of shaft. General 

 form of skull as in Hipposideros. Rostrum moderately swollen 

 and distinctly lower than braincase. Premaxillaries unusually thick, 

 forming along line of contact a distinct ridge which terminates 

 anteriorly in a noticeable backward-curved point. Zygoma greatly 

 expanded posteriorly, the expansion conspicuously narrowed above, 

 its height fully equal to distance between last molar and glenoid fossa. 

 Sagittal crest beginning at middle of posterior portion of braincase 

 (the hindermost rounded part of which is smooth) its height increas- 

 ing rather rapidly until slightly in front of middle of braincase it 

 reaches 1 mm. Here it abrupty ter- 

 minates in a forward-curved point. 

 In front of the crest the median re- 

 gion shows the usual ridges, but 

 these are so reduced as to be 

 scarcely visible by the unaided eye. 

 Tail well developed, longer than 

 femur. 



Species examined. — Rhinonycte- 

 ris aurantius (Gray). 



Remarks. — This genus is very 

 strikingly characterized by the 

 large secondary cusp of the upper 

 canine and the peculiar cranial 

 characters. 



Genus TRI^ENOPS Dobson. 



1871. Triwnops Dobson, Joufn, Asiat. 



Soc. Bengal, XI, p. 455. 

 1878. Triwnops Dobson, Catal. 



Chiropt. Brit. Mus., p. 123. 



Type-species. — Triwnops persicus 

 Dobson. 



Geographic distribution. — Madagascar, eastern Africa, and Persia. 



Number of forms. — Four species of Triamops are known. 



Characters. — Dental formula and general structure of teeth as in 

 Hipposideros, but upper incisors noticeably bifid and upper canine 

 with a secondary cusp extending nearly to middle of shaft. Skull 

 (fig. 22) with rostral portion greatly developed, much more than 

 half as long and nearly as deep as brain case, the anterior nares very 

 broad and with a short, but distinct, median spine on posterior border. 

 Zygoma greatly expanded throughout, but most conspicuously behind, 

 where the height is equal to distance between last molar and glenoid 



Fie. 22.— Tki/enops persicus. Aden, Arabia. 

 No. 123439. X-2. 



