PLATE XIII. 
PAGE 
Figs, la, lb. IXACANTHus STENTS Cope 16 
la. Lateral view of lumbar vertebra. Charles County near the Patuxent 
River. Acad. Nat. Sci., Phila. x % 
lb. Posteri»F view of the same specimen. x % 
Figs. 2-4. IXACAXTHUs SPiKOSus Cope 17 
2. Lower view of a posterior lumbar. Charles County near the 
Patuxent River. Acad. Nat. Sci., Phila. x % 
3a. Superior view of a cervical. Same locality and collection. X % 
3b. Anterior view of the same. x % 
4. Lateral view of an anterior lumbar. Same locality and collection. 
X % 
Figs. 5a-6. Ixaoaxthus ateopius Cope 18 
5a. Lateral view of a dorsal. Charles County on the Patuxent River. 
Acad. Nat. Sci., Phila. X % 
5b. Anterior view of the same. x % 
G. Lower view of a dorsal. Same locality and collection. x % 
