74 



Palaeontographica Americana 74 



PlvATE III 



Figure Page 



1. Area mississippicnsis Conrad 14 



Vicksburg Oligocene of Vicksburg, Mississippi; X 2; oblique view to show the 

 cardinal area. 



2. Exterior of same; X 2. 



3. Interior of the same; X 2. 



4. Area mississippiensis Conrad; Vicksburg Oligocene of Vicksburg, Mississippi. This 

 is close to A. marylandica. 



5. Area marylayidica Conrad 14 



OHgocene of Bailey's Ferry, Florida; form with two-angled posterior part. The 

 ribs of the posterior slope are inconspicuous, in contrast to the coarse posterior ribs 

 of A. eandida. 



6. Area marylandica Conrad; Oligocene of Bailey's Ferry, Florida; another form of 

 this species. 



7. Area marylandica Conrad; Oligocene of Bailey's Ferry, Florida; interior of an ir- 

 regular specimen, showing the close grooving of the cardinal area. 



8. Area areula Heilprin 15 



"Oligocene of Tampa silex beds; 47 mm." after Dall. 



9. Area areula Heilprin; after Heilprin. 



10. Area phalaera Dall 16 



"Oligocene of Oak Grove, Florida; 23 mm."; after Dall. 



11. Area eandida Gmelin 16 



Recent from Santo Domingo. This shows the character of the anterior, cen- 

 tral, and posterior ribs. 



12. Area eandida Gmelin; recent from Santo Domingo: interior of a shorter form. 



13. Area irregularis Dall 17 



"Pliocene of the Caloosahatchie marls; 52 mm."; after Dall. Since the name 

 irregularis is preoccupied this species has been renamed A. ealoosahatehiensis. 



14. 15. Area nodulosa Miiller 18 



* "Barholmen, Droebak" ; after Broegger. The indicated length of the figured 

 specimen is 9 mm. 



