1908.] DR. KNUD ANDERSEN ON BATS. 225 



Artibeus and Uroderma. — Artibeus differs from Uroderma in 

 the following particulars : — 



Skull short and broad. Rostrum conspicuously depressed ; 

 profile of skull, from front of sagittal crest to nasals, therefore 

 much concave (text -fig. 43, on p. 213); height of rostrum at p* 

 much less than width of skull at " postorbital" constriction (imme- 

 diately behind postorbital processes or their rudiments). Bony 

 palate shortei- : distance from palation to front of incisors always 

 less (generally very much less) than zygomatic width (text-fig. 43, 

 on p. 213). Median backwardly extending portion of bony palate 

 (behind last molar) shorter, not equal to the combined length 

 (externally) of m^ and nr, often equal only to the length of m'. 

 Plane of anterior nasal opening more oblique than in Uroderma. 



Inner upper incisors bifid, outer upper incisors simple. The 

 cingulum of the lower canine terminates, on the inner side, 

 about the level of the cutting-edges of the lower incisors, without 

 forming a cusp-like projection (text-fig. 48, on p. 216). Cusp 4 

 (anterior cusp) of p* practically completely wanting (for this and 

 the following dental characters see text-fig. 41, on p. 208). m^ 

 either quite rudimentary or, in most species, completely wanting ; 

 when present the tooth is situated postero-internally to m". As 

 a consequence of the small size and postero-internal position of m^, 

 cusp 5 of m" is decidedly more lingual in position, occupying, 

 pi-ecisely or very nearly, the middle of the posterior margin of the 

 tooth. Cusp 2 of m^ very strongly developed, rising as a high 

 slender cone near the middle of the lingual margin of the tooth. 

 In accordance with the rudimentary condition, or complete dis- 

 appearance, of m'', also nig is relatively smaller than in Uroderma, 

 or, in certain species, entirely wanting. 



No species of Artibeus has a narrow line of whitish fur down 

 the middle of the upper side. 



Artibeus and Enchisthenes. — Artibeus differs from Enchisthenes 

 chiefly in the following respects : — 



Cutting-edges of inner upper incisors bifid, not simple, pointed 

 in the centre, without any trace of a median notch, as in Enchis- 

 thenes. m^ rudimentary, situated postero-internally to ni" or, 

 most often, entirely wanting, not relatively large and situated 

 direct behind nr, as in Enchisthenes. vci., very small, equal to g-yg 

 of m" or entirely wanting ; in Enchisthenes equal to about | of 

 m^. — In no species of Artibeus is there any trace of a pointed 

 projection on the inner margin of the tragus. 



On the principal characters subject to specific variation. — (A) 

 Skull. — In the fourteen species referred to the genus Artibeus 

 in the present paper, three types of skull can be discriminated : — 



(1) The ordinary shape of the skulls, characteristic of all species 

 but three, is that figured on p. 213 (text-fig. 43) : rostrum 

 moderately depressed, profile of nasals, from base to tip, very 

 nearly horizontal (not slightly ascending), palate not shortened. — 



(2) In one species, A. concolor, the facial portion of the skuU is 



15* 



