92 ON THE STRUCTURES AND DISTRIBUTION OF THE 



Cystignathi, 



Hylodes, 



Ceratophrjdes, 



Pseudes, 



Pleurodemge, 



Criniae, 



There are then known twenty-five Australian species, of which all but two possess 

 an incomplete cranium, and none a bony xiphisternal style. In the Patagonian sub- 

 region thirteen species, of which ten exhibit an incomplete cranium, and five a com- 

 plete bony xiphisternal style. In the Brazilian subregion fifty-three species, of 

 which only six have an incomplete brain case, and twenty-four the osseous xiphister- 

 nal style. Mexico, three species with complete cranium, and one of these with 

 style ; the West Indies with eleven, none having the fontanelle, and three the style. 



E.Australis, S.R. Patachonica, S. B. Brasil., S.R. Mesic, S. R. Ind. Occ. 

 Total, 25. 13. 53. 4. 11. 



Prefrontals fully developed. 



Ear imperfect, 



No vomerine teeth. 



Toes webbed, 



Fossorial shovel. 



In regard to the cranial development, the West Indian region is preeminent in 

 this family as in the Hylidaj, the Brazilian inferior, and the Australian vastly below 

 all ; the degradation appearing in a certain degree regular. In the lack of vomerine 

 teeth, (a feature of immaturity,) the Australian forms predominate. In possession of 

 the Raniform xiphisternum the West Indian and Mexican subregions show fewer 

 representatives than the Brazilian. 



One species, — Lithodytes ricordii, — wanders from the R. Neotropica into the 

 southern projection — Florida — of North America; no others are known to occur 

 beyond the borders already stated. No species is common to the R. R. Australis and 

 Neotropica, and but one genus, — Borboroca^tes. Two Brazilian species occur in the 

 Southern West Indies, and two in Southern Mexico; probably three of the same 

 country must be included in the Buenos Ayrean list. 



The whole number of species must be reckoned at 108, which fall into 35 genera. 



As yet we are acquainted with the fossil remains of but one species of Cystigna- 

 thidae, — a Ceratophrys, from a Brazilian cave. It has been regarded as identical 

 with the C. dorsata by Giinther, Ann. Mag. Nat. Hist. 1859, pi. xv. 



