282 PROCEEDINGS OP THE ACADEMY OF 



Comparing the genera in a general physiological sense we may parallelize 

 further. 



Aquatic, with digital dilatations. 



Heteroglossa. Acris. 



Arboreal; cranium hy-poiypedates. Trachycephalus. 

 perostosed. •'^ •' ^ 



" cranium free. T,, , ( Hyla. 



Rhacophorus. j Agalychnis. 



The same kind of parallels exist between the primary groups of the Testu- 

 dinata, as follows : 



Crtptodira. Pleurodira. 



Five complete pairs of boues across the plastron. 



Pleurosternidas. Sternothaeridse. 



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. 



Emydidffi. Podocnemididse. 



Temporal fossa overroofed by parietal. 



Macrochelys. Podocnemis. 



No zygoma ; a parieto-mastoid arch. 



* * * Hydraapididae. 



If we compare the peculiarities 'of generic structure merely with reference 

 to their adaptation to the animals habits, we will see the following : 



Cryptodira. Pleurodira. 



Feet reduced for terrestrial progress. 



Testudinidae. Pelomedusidae. 



Feet normal. 



Anterior lobe of sternum moveable. 



Cistudo. Sternothaerus. 



Cinosternum. 

 Anterior lobe fixed. 

 Neck very elongate. 



Trionychidae. Chelodina. 



Neck shorter ; aquatic. 

 Temporal fossa open. 



Emydidae in gen. Hydraspididas. 



Temporal fossa over-roofed. 



Cheloniidae. Podocnemis. 



The parallels between the genera of the American Iguanidae and the old 

 world Agamidae are similarly quite close. 



Iguanid.*:, Agamid^. 



Abdominal ribs. 



^ Polychrus. ■ * * 



No abdominal ribs. 



Ribs greatly prolonged into a lateral wing. 



* * Draco. 



Ribs not prolonged. 



Arboreal types, generally compressed. 



A dorsal and caudal fin supported by bony rays. 



Basiliscus (no fern, pores) Lophura (pores.) 

 No vertebral fin. 



[Oct. 



