ON THE OEIGm OF GENERA. 



97 



Arboreal; vom. teeth. 



" no « " 

 Subarboreal. 



Terrestrial. 



" spurred, 



Kaniformes. 

 Leptopelis. 

 Hyperolius. 

 Hylambates. 



Feet not webbed. 

 Cassina. 

 Hemimantis. 



Arciferi. 

 Hvla. 

 Hylella. 



Nototrema. 



Cystignathus. 

 Gomphobates. 



Comparing the genera in a general physiological sense, we may 

 parallelize further. 



Aqviatic, with digital dilatations. 



Ileteroglossa. 



Arboreal : cranium hy- ) t> , , , 



' 4. ^ [ Polypedates. 



perostosed. ) •' ' 



" cranium free. Ehacophorus. 



Acris. 



Trachycephalus. 



j Hyla. 



I Agalychnis. 



The same kind of parallels exists between the primary groups 

 of the Testudinata, as follows : 



Crtptodira. Pleurodira. 



Five complete pairs of bones across the plastron. 



Pleurosternidae. Stemothaeridae. 



Four pairs of bones across plastron ; not more than two phalanges on all toes. 



Testudinidae. Pelomedusidae. 



Three phalanges on most digits ; 

 Zygomatic arch ; no parieto-mastoid. 



Emydidae. PodocnemididaB. 



Temporal fossa over-roofed by parietal. 



Macrochelys. Podocnemis. 



No zygoma ; a parieto-mastoid arch. 



* * * Hydraspididae. 



If we compare the peculiarities of generic structure merely 

 with reference to their adaptation to the animals' habits, we will 

 see the following : 



Crtptodira. 

 Feet reduced for terrestrial progress. 



Testudinidae. 

 Feet normal. 



Anterior lobe of sternum movable. 



Cistudo. 

 Cinostemum. 

 Anterior lobe fixed. 

 Neck very elongate. 



Trionychidae. 

 Neck shorter ; aquatic. 

 Temporal fossa open. 



Pleurodira. 

 Pelomedusidae. 



Sternothaerus. 

 Chelodina. 



Emvdidae in gen. 



Temporal fossa over-roofed. 



Cheloniidae. 



Hydraspididae. 

 Podocnemis. 



The parallels between the genera of the American Iguanidae 

 and the Old World Agamidoe are similarly quite close. They are 

 shown on Plates II and II a. 

 1 



