EXPLANATION OF PLATE XVIL 



Superior cranial walls of Pylliouomorplia, from btlow aud above, one-half natural size. 



Fig. 1. CliOastes tortor, from below. 



2. Platecarpus cnrtirostris, from below. 



3. Plaiicarpus iclericiis, from below. 



4. Platccarpus iciericus, from above. 



5. Platccarpus mitdgei, from below. 



G. Platccarpus coryphaus, from below. 



7. Clidastes stowps, from below, without prefrontal bone. 



8. Clidastes stcnops, from aljove, with right prefrontal bone. 



