THE FAMILIES AND GENERA OF BATS. 171 



specialized. In the reduction of the rostrum Sphwronycteris has 

 certainly proceeded further ; this is also true of the plate-like develop- 

 ment of the anterior edge of orbits and of the widening and upward 

 bending of the zygomata. On the other hand the persistence of the 

 .third lower molar is a more primitive character, the form of the 

 upper canine and of the palate is less aberrant, and the development 

 of the dermal outgrowths on face is much less extreme. 



Genus AMETRIDA Gray. 



1847. Ametrida Gray, Proc. Zool. Soc. London, p. 15. 

 1878. Ametrida, Dobson, Catal. Chiropt. Brit. Mus., p. 530. 



Type-species. — Ametrida centurio Gray. 



Geographic distribution. — Tropical South America. 



Nximber of forms. — Two species are now known. 



Characters. — Differs from Sphceronycteris in the presence of a 

 small but normally formed noseleaf , in the still greater shortening of 

 the rostrum, so that flat space in front of nares is wider than distance 

 between canines, in the retraction of the anterior wall of orbit until 

 orbital space is wider than long, in the presence of a mere bead along 

 anterior rim of orbit, and in the practical absence of any interptery- 

 goid space, the pterygoids being directed almost perpendicularly out- 

 ward and the choanas opening between them as a rounded vertical 

 aperture facing backward. Teeth essentially as in Sphceronycteris, 

 but upper incisors smaller and inner cusps of upper molars better 

 developed, though in the same position. Minute third lower molar 

 present as in Sphceronycteris. 



Species examined. — Ametrida centurio Gray and A. minor H. Allen. 



Remarks. — Of the three related genera, Ametrida, Sphceronycteris, 

 and Centurio, the first is 'externally the least modified, retaining as it 

 does its practically normal noseleaf. In dental characters it agrees 

 with Sphceronycteris, which is in this respect less aberrant than 

 Centurio. Its skull, however, is the most peculiar of the three, show- 

 ing the greatest extreme of rostral shortening, and in addition having 

 a structure of the choanse that is unique among bats. 



Subfamily PHYLLONyCTEEIN^. 



1865. Glossophagce (part) Petebs, Monatsber. k. preuss. Akad. Wissensch., 



Berlin, p. 257. 

 1875. Glossophagce (part) Dobson, Ann. and Mag. Nat. Hist., 4th ser., XVI, 



p. 350, November, 1875. 

 1878. Glossophagas (part) Dobson, Catal. Chiropt. Brit. Mus., p. 497. 

 1886. Glo&sophaginw (part) Gill, Standard Natural History, V, p. 173. 



1891. PhyllostomatincB .(part ; Glossophagine division, part) Flower and 

 Lydekkek, Mammals, living and extinct, p. 672. 



1892. Glossophagce (part) Winge, Jordfundne og nulevende Flagermus 

 (Chiroptera) fra Lagoa Santa, Minas Geraes, Brasilien, p. 24. 



1898. Brachyphyllina (part) H. Allen, Trans. Amer. Philos. Soc, n. s., XIX. 

 p. 258. 



