PLATE XXXIX. 



CARBONIFEROUS SPECIES. 



Fig. 



1. Productus giganteus, Martin. Dorsal valve and beak of ventral one. Car- 



boniferous limestone near Richmond, York- 

 shire, and collection of Mr. E. Wood. 



2. ,, ,, A smaller specimen. Same locality. 



3. „ ,, A very circular variety. 



4. „ ,, An evenly convex variety, P. matdmus, M'Coy. Carboni- 



ferous limestone near Cork, Ireland. 



5. „ „ A young example. Yorkshire. 



