GENERA OF THE ARCIFEROUS ANURA. 87 



In the series 1 — 2 to Phyllomedusa a final diminution of palmation accompanies 

 continued size of the digital pallettes and increase in the length and breadth of the 

 ethmoid, and diminution of the frontoparietals, which features, however, are as 

 marked in Hyla p a 1 m a t a as in these succeeding types : they carry to its fullest 

 developement the cranial peculiarities of the family, and add other features before 

 mentioned ; they inhabit the continental subregion of the Neotropical. The other main 

 series (3 — 4) leads, first, to a fuller developement of the frontoparietals, then to an ex- 

 tension of the prefrontals, and finally to covering of the cranium with " dermoossifi- 

 cation," on the one hand with the superaddition of a dorsal dermal sac, on the other 

 without it. This extreme finds its greatest expansion in the West Indian subregion. 

 A singular incompleteness of the cranial box seems to mark Thoropa, which has the. 

 strong nasal roofing of this second series. 



Chorophilus exhibits an affinity to the Cystignathidge, as does also Thoropa, which 

 represents in inferiority Eusophus in the same family. 



The following is the geographical distribution of the genera and species : 





R. 



R. 



R. 



R. 



R. R. 





Australis, 



Neotropica, 



Nearctica, 



Palaearctica, 



Aethiopica, Palsotropica, 



Triprion, . 





. 1 









Opisthodelphys^ 





. 1 









T r achy ceph al us, 





. 9 









Osteocephalus, 





. 2 









Nototrema, 





. 1 







V 



Scytopis, 





O 









Ranoidea, 



. 1 











Dryomelictes, 





. 1 









Pithecopus, 





. 2 









Phyllomedusa, 





. 2 









Agalychnis, 





. 4 









Smilisca, . 





. 1 









Hyla, . . 



. 17 



. 62 



12 



1 



(2 froni withoutj 



Hylella, . 





. 2 









Acris, * . 



• 



. 



. 1 







Chorophilus, 



. 





. 5 







Thoropa, 





. 1 









Total, 131. 



18 



93 



18 



(2) 



