250 DR. KNUD ANDERSEN ON BATS. [Apr. 7, 



respect, is slightly more primitive than the latter gi'oup. Other 

 facts, to be mentioned hereafter, point to the same effect. 



Teeth. — As in A . planirostris, with the following differences : — 

 m'', which is rudimentary in A. planirostris, has definitely 

 disappeared in A. javiaicensis. 185 skulls, of the seven sub- 

 species recognised in this paper, and of practically all ages, from 

 half-grown to very old individuals, have been examined ; all of 

 them lack m^ and in none is there any trace of the tooth having 

 been present. 



mg is on the whole still somewhat smaller than in A. plani- 

 rostris. When, as is the case in A. jamaicensis, the development 

 has reached the point that m^ is invariably wanting and mg 

 reduced to a mere rudiment, it might be anticipated that this 

 rudimentary mg would, pi-obably, show some tendency towards 

 complete disappearance. But it must be said at once that indi- 

 viduals lacking nig on both sides of the jaw, without any trace of 

 its alveoli, are extremely rare ; the remarkable fact is not that 

 such exceptions do occur, but, in view of the minute size of the 

 tooth, that they do not occur more often. In two individvials 

 (a young adult A. j. jamaicensis from San Domingo, B. M. 

 no. 50.7.8.43 ; and a fully adult male, with unworn teeth, of the 

 same race from Peten, Guatemala, U.S. N. M. no. 37912) mg is 

 entirely wanting on oire side ; in four individuals (an adult 

 male, with somewhat worn teeth, of A. j. palmarum from Costa 

 Rica, B.M. no. 98.10.9.4; a young female of A. j. jamaicensis 

 from Oaxaca, Mexico, U.S. N. M. no. 73255 ; an aged male, with 

 much worn teeth, of A. j. jamaicensis from Morelos, Mexico, 

 U.S. N. M. no. 64482 ; and an adult male, with unworn teeth, 

 or the same race from Old Providence Island, U.S. N. M. 

 no. 37811) it is wanting on both sides. Thus in 97 p. ct. of the 

 185 skulls examined m^ (or its alveolus) is present on both sides, 

 but averaging a little smaller than in A . planirostris, in 3 p. ct. 

 it is completely wanting either on one side or on both sides. 



In those few species of Artibeiis which have preserved a rudi- 

 mentary m% this tooth is situated postero-internally to m", partly 

 fitting into a sharp, subrectangular emargination in the posterior 

 border of this latter tooth, between its cusps 5 and 7 (text-fig. 41 A, 

 on p. 208), What becomes of this angular notch, when, as is 

 invariably the case in A . jamaicensis, m^ completely disappears ? 

 It is an interesting fact that in the i-aces of northern origin 

 (^A, j. parvipes, yucatanicus, jam^aicensis, ceqiiatorialis) the emar- 

 gination is, in 77 p. ct. of the individuals, preserved quite or 

 almost as conspicuous as in any A. planirostris, sometimes (in 

 about 19 p. ct.) it is decidedly reduced in size, rarely (4 p. ct.) 

 almost or quite disappeared ; whereas in the races of southern 

 origin {A . j. lituratus, palmarum, dominicanus) the emargination 

 has only been preserved, as conspicuous as in ^ . planirostris, in 

 about 10 p. ct. ; in 38 p. ct. it is decidedly on the way towards 

 disappearance, in 52 p. ct. it has practically disappeared. Thus, 

 the northern races, though having like their southern relatives 



