EXPLANATION OF PLATE LI. 



Figs. 1-7. Pachyrhizodus latimenlum, Cope, three-fourths of natural size. 



Fig. 1. Both mandibular rami, the upper without articulo-angular bone ; the lower with the upper edge 



downward, and the distal eDd of the dentary wanting; 1 a, symphyseal extremity of the 



left dentary ; 1 b, probable accessory maxillary bone. 



2. Supposed preorbital hone. 



3. Elemeut of uncertain position. 



4. Supposed hyomandibular ; on the same block as the next — fig. 



5. Supposed interoperculum. 



6. Uncertain piece, perhaps symplectic. 



7. Lateral view of a vertebra accompanying the same. 



8. Pachyrhizodus leplopais, Cope, mandibular ramus, natural size: a, distal half of dentary bone, 



from within ; 6, proximal part of the same bone ; c, vii w of distal or symphyseal end of the 

 same. 



