SHELLS OF ORMOND MOUND. 173 



ers of the mound. It is a Pliocene species 

 which yet occurs along the coast from Vir- 

 ginia southward. 



18. Unio obesm blandingianus Lea. A number of 



the valves of this fresh-water form were scat- 

 tered throughout the mound. The epidermis 

 had wholly disappeared. It occurs in streams 

 throughout Florida, and northward to south- 

 ern Virginia. 



19. Unio occultus Lea. A few valves of this Unio 



were taken mingled with those of the last 

 named species. It is known only from Flor- 

 ida streams. 



20. Unio coruscus Gld. Several valves of this Unio 



were secured by Professor Hitchcock. It is 

 known only from the streams of Florida. 



21. Unio sp.f One valve of a Unio, distinct from 



any of the above, was found by Mr. Simpson 

 among the specimens submitted to him. 



22. Anodonta imbecillis Say. A number of worn 



and partly decayed shells of this handsome 

 fresh-water form were present. According 

 to a note by Mr. Simpson, it is not at present 

 known to occur south of North Carolina. 



23. Area americana Gray. 



24. Area ponderosa Say. Numerous valves of these 



two marine bivalves were found in all the lay- 

 ers of Donax shells. They are now common 

 along the beach opposite the mound. 



