GENERA OF THE ARCIFEROUS ANURA. 85 



With vomerine teeth, . . . . . . . . . . .128 



With postfrontal arch, ........... 1 



Ethmoid arch complete, . . . . .. . .. .130 



Of the above characters, the lack of vomerine teeth is inconstant in Pithecopus, 

 being present in one, and wanting in another species. 



There is a tendency to the Pseudis and Rana liberation of the outer metatarsus in 

 Hyla americana, hyposticta and dimolops, and Ranoidea' a u re a . 



Parotoid glands occur in somespecies of Hylidse as an extensive stratum of crypts, 

 but never exhibit the definition seen in Bufoniform and some Cystignathid genera. It 

 even occurs in Scy topis venulosus irregularly, being sometimes preseiit, and 

 sometimes wanting, in the female at least. 



The xiphisternum exhibits the form which exists in the greater number of Cys- 

 tignathidse, excepting in eight species, where it only lacks the posterior emargination. 



The natural genera are as follows : 



I. No frontoparietal fontanelle. 



a. Cephalic derm occupied by the external rugosities of the 

 cranial bones : prefrontals in contact. 



A series of parasphenoid teeth or acute serrations ; vomerine teeth. 



No dorsal sac ; labial margin much prolonged, . . . Triprion. 



Vomerine teeth ; no parasphenoids or dorsal pouch, . . . Trachycephalus. 



Vomerine teeth ; a dorsal pouch ; no parasphenoids, . . . Opisthodelphts. 

 aa. Skin free from the surface of the cranium. 



A dorsal dermal pouch in ? ; prefrontals partly united : vomerine 



teeth ; dilatations small, ....... Nototrema. 



No dorsal dermal pouch ; prefrontals united ; cranium with i 



caringe; vomerine teeth, . . . . . " . . Osteocephalus. 



No dorsal pouch ; prefrontals united ; no cranial carinfe ; vomer- 

 ine teeth, ScYTOPis. 



No dorsal pouch ; prefrontals narrow, well separated ; outer meta- 

 tarsi bound ; a ? coccygeal diapophysis ; vomerine teeth, . . Drtomelictes. 



No dorsal pouch ; vomerine teeth ; outer metatarsi slightly free ; 



no coccygeal diapophysis, ....... Ranoidea. 



II. Frontoparietal bones embracing an extensive fontanelle. 

 a. A dagger-shaped postorbital process of the frontoparietal 



bone. 

 Vomerine teeth ; form stout, feet webbed, ..... Sjiilisca.* 

 aa. Frontoparietal simple. 



* Species, S. b a u d i n i i [Hyla baudinn 1). .lud B.) ; tlip name " dauliniu " must probably be considered an 

 erroneous orthograpby of the same. 



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