256 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



The generic forms are all peculiar to their zoological regions, except 

 Hyla, found wherever its family occurs, and Borborocoetes, common to 

 Australia and the southern portion of South America. 



The number of species so far known to inhabit these regions is as 

 follows : 



Regio Australia 55 



E. Neotropica 363 



K. Nearctica 28 



Total 446 



Iq two regious -... 1 



446 



R. Pakeartica 12 



R. JEtliiopica u . 9 



E. Palseotropica 50 



Total 517 



lu two regions 2 



The small proportion of species occurring in the Old World, exclu- 

 sive of Australia, ii? evident, though they represent six families, while 

 those of the New World represent but six also. 



The tribe Arcifera was first defined and its extent and distribution 

 indicated by the author in the Natural History Eeview, 1865, though 

 explained a year previously at a meeting of the Zoological Society of 

 London. The sternal feature characterizing it was noticed by Steet- 

 zeii, (Juvier, and others in isolated cases, but its general significance 

 not perceived. Duges (Kecherches, 64) attributes it to the tree- toads, 

 the toads, and the Bombiuator, Alytes, and Pelobates. In Stannius';s 

 Zootomie der Amphibien (73) it is assigned to tlie Aglossa and Bufo, 

 as distinguished from Eaiia and Cystignathus. The characters of the 

 last genus must have been taken from the Old World Cassina (formerly 

 called Cystignathus), as the structure in Cystignathus and its allies is 

 that of the true Arcifera. 



DlSCOGLOSSlDJi:.* 



Cope, Nat. Hist. Rev., 1865 (Jan.) ; Journ. Pliila. Ac, 1866, p. 74 ; Lataste, 

 Actes de la Soc. Linn, de Bordeaux, 1879, p. 277; Boulenger, Cat. Batr. 

 Sal. Brit. Mus., 1882, 444. 



Vertebrae opisthocoel. t Diapophyses of sacrum dilated. Urostyle 

 with a basal diapophysis. Ribs present.| Bones of distal carpal series 

 all distinct. Sternum of two slender postero-exteriorly diverging fibro- 

 cartilaginous or cartilaginous styles. 



In the known genera tongue is round, entire, and little or not at all 

 free behind. Males without vocal vesicle. 



A marked peculiarity characterizes the larvae of this family. The 

 spiracle or branchial opening is situated on the median line below, 

 while in all other tongued Anura it is situated on the left side. 



If we commence the series of the Arcifera with the great family of 

 the Cystignathidae, we will end it with the families Asterophrydidae 

 and Discoglossidae, which are perhaps equally connected witb that 

 which precedes them — the Scaphiopodidae. The former leads to Xen- 

 opus through Palaeobatrachus ; the latter, as far as our present knowl- 



* Plate 78. ~^^~~~~~~~~ 



t Observed by Duges and Gervais in Alytes. 



X Observed by Duges in Alytes and Bombiuator, and by Diini6iil in Discoglossus. 



