6. CIIRYSEMYS. 71 



hind lobo more than two thirds tlio width of tho carapace ia 

 the adult ; carapace smooth, without trace of a keel, even ia 

 the young. 



Vertebrals 2 to 4 with tho antoro-hitcral 

 borders much shorter than tlie postero- 

 lateral 1. pto^a, p. 72. 



Vertebrals hexagonal, tlie antero-latcral 

 and postcro-latcral borders subequal in 

 length 2. cinerea, p. 73. 



E. The width of the liind i)lastral bone not more than two thirds 

 the width of the carapace ; latter keeled in the young. 



1. Interorbital space hardly half tho 



horizontal diameter of the orbit . 3. reticulata, p. 75. 



2. Head very small ; shell very much 



depressed, smooth or nearly so iu 

 the adult. 



Posterior border of carapace scarcely ser- 

 rated 4. troostii, p. 76. 



Posterior border of carapace serrated .... 5. Iiierorjhjpluca, p.70. 



3. Head moderate or large. 



a. Snout short, obtuse, feebly projecting ; nostrils terminal. 



Posterior border of carapace serrated, each 



marginal being notched ; dorsal shields 



longitudinally rugose in the adult .... G. scripta, p. 77. 

 Posterior marginals notched ; cai-apacc 



nearly smooth in the adult 7. dorhlgnyi, p. 80. 



Posterior marginals not notched ; dorsal 



shields longitudinally rugose in the adult. 8. ornata, p. 80. 



h. Snout pointed, strongly project- 

 ing, nostrils below the end of 

 the snout 9. rjraiji, p. 82. 



II. Alveolar surface of upper jaw very broad all round, with a 

 strong, tuberculate or serrated median ridge ; outer surface of 

 mandible flat. 



Beak scarcely emarginate mcsially ; edge of 



jaws not or but very slightly serrated . . 10. concinna, p. 83. 



Beak notched mesially, with a prominent 

 cusp on each side ; edge of both jaws 

 strongly serrated 11. rubriventris, p. 84. 



Beak deeply notched mesially, with a pro- 

 minent cusp on each side ; edge of upper 

 jaw finely serrated, of lower jaw more 

 strongly and more coarsely 12. mobiliensis, p. 85. 



