6. CHRYSEMYs. 71 
hind lobe more than two thirds the width of the carapace in 
the adult; carapace smooth, without trace of a keel, even in 
the young. 
Vertebrals 2 to 4 with the antero-lateral 
borders much shorter than the postero- 
abe raliearton sey Sacro Se eee cea kee Seca oe 1, picta, p. 72. 
Vertebrals hexagonal, the antero-lateral 
and postero-lateral borders subequal in 
Teme Ghe gc schon ajo) ge Me we oe ae mieerd acess 2. cinerea, p. 73. 
BL. The width of the hind plastral bone not more than two thirds 
the width of the carapace ; latter keeled in the young. 
1. Interorbital space hardly half the 
horizontal diameter of the orbit . 3. reticulata, p. 75. 
2. Head very small; shell very much 
depressed, smooth or nearly so in 
the adult. 
Posterior border of carapace scarcely ser- 
TALL beasts asl tabs hen scat Snenay c fap etal sence 4. troostii, p. 76. 
Posterior border of carapace serrated .... 5. hieroglyphica, p.76. 
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 .... 6. seripta, p. 77. 
Posterior marginals notched ; carapace 
nearly smooth in the adult ......... 7. dorbignyi, p. 80. 
Posterior marginals not notched; dorsal 
shields longitudinally rugose in the adult. 8. ornata, p. 80. 
b. Snout pointed, strongly project- 
ing, nostrils below the end of 
tHERSMOUE! Uyayvetsiae wal sbalete ss 9. grayt, 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 mesially ; 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 
SuLOMelyeserrabedcn sora -lele yy cima tes 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, 
