LIST OF ILLUSTRATIONS 



Plates 



I. — Skull and Lower Jaw of Isolohodon portoricensis gen. et sp. nov. 

 II. — Lower Jaw and Dentition of Isolohodon portoricensis gen. et sp. nov. 

 III. — Scapula, Humerus, Ulna and Radius of Isolohodon portoricensis gen. et 



sp. nov. 

 lA'. — Sacrum of Isolohodon portoricensis gen. et sp. nov. 



V. — Femur and Tibia of Isolohodon portoricensis gen. et sp. nov. 

 VI. — Map Showing the Distribution of the Morrison Formation. 

 VII. — Right Femur of Acratocnus odontrigonus. 

 VIII. — Limb Bones of Acratocnus odontrigonus. 



IX. — Limb Bones and Vertebrae of Acratocnus odontrigonus. 

 X. — Skull of Acratocnus odontrigonus. 

 XL- — Skulls of Acratocnus odontrigonus and Heteropsomys insulans. 

 XII. — Skull of Heteropsomys insulans. 

 XIII. — Skull of Elasmodontomys ohliquus. 

 XIV. — Skull of Elasmodontomys ohliquus. 



Text Figures 



Page 



fBalithcriitm antillensc, lower jaw. left ramus, type specimen 25 



fHalithcrium antillense, parts of cervical (right) and anterior dorsal (left) 



vertebrjB of type specimen 27 



Generalized section of Rocky Mountain hog-back, showing the usual physi- 

 ographic position of Morrison outcrops 42 



Generalized section of a Rocky Mountain or Great Plains river canyon, 



showing a common position of Morrison Outcrops 42 



Section of the Morrison and overlying and underlying beds at Laporte, 



Colorado 46 



Section of the Morrison and adjacent formations east of Lyons, Colorado. . 46 



The Morrison formation at Morrison, Colorado, looking south 47 



The Morrison formation at Morrison. Colorado, looking east 48 



View northeast from Fremont Peak, near Cafion City, Colorado 49 



Site of the Marsh -Hatcher dinosaur quarry near Canon City, Colorado 50 



Near view of the central portion of the above 50 



Exposure of the lower beds of the Morrison formation about 100 yards 

 northeast of the Marsh-Hatcher dinosaur quarry, near Canon City, 



Colorado 51 



The Cope dinosaur quarry northwest of the Marsh-Hatcher quarry, near 



Canon City, Colorado 52 



The "Nipple," west of Garden Park, Colorado, looking east 53 



Section of the Morrison and related formations at Garden Park, near 



Canon City, Colorado 55 



Upper part of the Garden Park section 55 



iv 



