20. TESTUDO. 153 



Nuchal miuuto ; lateral marginals formin 

 an anglo with the costals ; beak feebly 

 hooked 13. trimeni, p. 103. 



b. A large subconical tubercle on tlie liiuder side oi' tho 

 thigh. 



Nuchal minute; beak strongly hooked. . . . 14. tcntor'ui, p. 104. 

 Ucak feebly hooked ; suture between the 



gulars nearly as long as that between the 



anals 15. smithii, p. 105. 



Beak feebly hooked ; suture between tho 



gulars much shorter than that between 



the anals 10. fislcii, p. 105. 



Beak strongly hooked ; nuchal ratlicr large, 



broadest posteriorly ; posterior margin of 



cai'apace strongly serrated 17. ocidifcra, p. 165. 



2. A pair of very large prpef rental 

 shields; shell hemispherical; gular 

 region of plastron more or lesa 

 produced 18. radlata, p. 166. 



V. Long-necked, gigantic tortoises of uniform dark brown or black 

 coloration. 



A. Nuchal shield present ; gular shields distinct. 



1. Shields of carapace concentrically 



striated, and plastron notched 



behind in the adult 19. elej)7tantina, p. 167. 



2. Shields of carapace smooth and plastron truncate behind in 



the adult. 



a. "Width of plastral bridge two fifths the length of the 

 carapace, which is declivous in front. 



Supracaudal shield divided 20. f/ir/antca, p. 168. 



Supracaudal shield undivided 21. holoUssa, p. 108. 



h. Width of plastral bridge one third 

 the length of the carapace, the 

 anterior profile of which is 

 nearly horizontal 22. daudinii, p. 169. 



B. Nuchal absent ; gulars distinct. 



1. Shields of carapace concentrically striated in the adult. 



Plastron notched behind ; profile of carapace 



declivous in front 23. nif/rita, p. 109. 



Plastron truncate behind in the adult ; pro- 

 file of carapace declivous in front 24. nigra, p. 170. 



