PLATE XLIX. 



Fig. Page. 



1. Ptychodus polygyrus, Agassiz; associated upper teeth of rows o' to iv', 



crown-views, with one tooth of o' in side view, and an outline-section 

 of the crown of one tooth in each other row, nat. size. — Zone of 

 Micraster coranguinum ; Banstead, Surrey. B. M. no. P. 10771. 233. 



2. Ditto ; lower teeth of rows o to n of the same specimen, crown-views 



and two outline-sections, nat. size. 234. 



3. Ditto; teeth of three lateral paired rows of the same specimen, crown- 



views, nat. size. 2o4. 



