INDEX OF PLATES. rrn 



PLATE 20. 



1. Baena emilia. Carapace of type. X 0.4. No. 1925 A. M. N. H. 



2. Baena emilice. Plastron of type. X 0.4. 



PLATE 21. 



1. Eubaena cephalica. Skull forming type, upper aspect. X i. No. 2110 Yale Univ. coll. 



2. Eubaena cephalica. Same skull, lower aspect. X i. 



3. Chlstcrnon hcbraicum. Skull, upper aspect. X i. No. 5961 A. M. N. H. 



4. Chisternon hebraicum. Same skull, lower aspect. X i. 



PLATE 22. 

 Chisternon undatum. Carapace. X 0.34. No. 3932 A. M. N. H. 



PLATE 23. 



1. Chisternon hebraicum. Skull, right side. X i. No. 5961 A. M. N. H. 



2. Bothremys cooki. Skull of type, lower surface. X 0.8. Type in Rutgers College, N. J. 



3. Bothremys cooki. Lower jaw of type. X 0.8. 



4. Osteopygis chelydrinus. Seventh peripheral of type. X 0.75. Xo. 1131 A. M. N. II. 



5. Osteopygis chelydrinus. Same bone, inner surface. X 0.75. 



6. Osteopygis chelydrinus. Second left peripheral of type, outer surface. X 0.75. 



7. Osteopygis chelydrinus. Same peripheral, inner surface. X 0.75. 



PLATE 24. 

 Thescelus insiliens. Carapace of type. X ! / 3 . No. 1108 A. M. N. H. 



PLATE 25. 

 Thescelus insiliens. Plastron of type. X y 3 . No. 1108 A. M. N. H. 



PLATE 26. 



1. Osteopygis gibbi. Rim of carapace of type, seen from below. X 0.23. Type in Yale. 



Drawing furnished by U. S. Geol. Surv. 



2. Osteopygis erosus. Sixth to tenth peripherals. X 0.27. No. 1130 A. M. N. H. 



3. Osteopygis borealis. Seventh to eleventh peripherals. X 0.27. No. 1132 A. M. N. H. 



PLATE 27. 



1. Osteopygis gibbi. Carapace of type. X l /t, -\-. Type in Yale Univ. coll. 



2. Osteopygis gibbi. Plastron of type. X % +. 



PLATE 28. 



1. Osteopygis chelydrinus. Third peripheral of type, outer surface. X 0.75. No. 113: 



A. M. N. H. 



2. Osteopygis chelydrinus. Same peripheral, inner surface. X 0.75. 



3. Osteopygis chelydrinus. Lower jaw, upper surface. X 0.75. Part of type. 



4. Osteopygis chelydrinus. Same jaw, right side. X 0.75. 



5. Lytoloma angusta. Lower jaw accompanying type peripheral. X 0.6. No. 1133 A. M. N. H. 



6. Lytoloma angusta. Peripheral forming type. X 0.6. No. 1133 A. M. N. H. 



7. Lytoloma wielandi. Upper surface of front of skull, forming type. X 0.8. Yale Univ. 



coll. Drawing from U. S. Geol. Surv. 



8. Lytoloma wielandi. Same specimen, lower surface. X 0.8. 



PLATE 29. 



1. Lytoloma wielandi. Type fragment of skull, seen from behind. X 0.8. 



2. Rhetechelys platyops. Skull forming type, upper surface. X 0.4. Type in coll. Phila. 



Acad. 



3. Rhetechelys platyops. Same skull, inferior surface. X 0.4. 



