206 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
Genus SCOTOZOUS Dobson. 
1875. Scotozous Dobson, Proc. Zool. Soc. London, p. 372. 
1878. Scotozous Dobson, Catal. Chiropt. Brit. Mus., p. 243 (subgenus of 
V esperugo ) . 
Type-species. — Scotozous clormeri Dobson. 
Geographic distribution . — India and northwestern Africa. 
Number of forms. — Four, Scotozous dorm,eri Dobson, S. ruppelii 
Fischer ( = V esperugo temminckii of Dobson), S. pidcher Dobson, 
and S. deserti (Thomas). 
Characters . — Like Pipistrellus , but with outer upper incisor very 
minute, its acutely pointed tip not extending beyond cingulum of 
inner. The small tooth lies external to the line between canine and 
inner incisor, and the large tooth is separated from canine by a space 
less than half its breadth. Premaxillary shortened proportionately 
with reduction of incisors. Upper canine without secondary cusp. 
Cheek teeth normal. 
Species examined. — Scotozous dormeri (Dobson), S. ruppelii 
(Fischer), and A. deserti (Thomas). 
Remarks . — In Scotozous ruppelii the inner upper incisor is strongly 
bicuspid (in dormeri it is simple) and the premaxillary is less 
shortened. The small outer incisor is, however, exactly as in S. 
dormeri. 
Genus IA Thomas. 
1902. la Thomas, Ann. and Mag. Nat. Hist., 7tb ser., X, p. 163, August, 1902. 
Type-species. — la io Thomas. 
Geographic distribution . — Southern Hupeh, China. 
Number of forms . — Only the type species has yet been discovered. 
Characters . — Similar to Scotozous , but differing in the form of the 
outer incisor, the crown of which is flat, with well-developed cingulum 
and barely indicated central elevation, and in the less development of 
the mesostyle in m 1 and m 2 , this cusp barely extending outward 
to line joining extremities of parastyle and metastyle, while in the 
related genera it extends distinctly beyond. The size of the only 
known species is much greater than in the members of the genus 
Scotozous / greatest length of skull 27 mm. instead of about 14 mm. 
Species examined. — la io Thomas. 
Remarks . — The relationship of la to Scotozous is undoubtedly very 
close, but the dental characters are perhaps sufficient to keep the 
genera separate. The difference in aspect clue to the great size of 
la io is very striking. 
