- 12 6 - 



forms, left v.^lves in oartien.lar, are more inflated than the typic- 

 al form and have more deeply channeled interspaces. 



This is the species which &upny identified as A. sonsohrina 

 Sovi,'erby (not A. consobrina d'Orhip-ny), •;7hieh was described from 

 Sa.nto Domingo. The relations between hall ^. on at a and SowerbyAs 

 oonsobil na and the question of noraenclat'!:ire is discussed under the 

 folloviang variety. 



Occurrence .- Upoer Oligocene.- Ouracao (Dall, 1898) Gumana, 

 Venezuela (Gupoy, 1874). Lop/er I.'iocene : Bowden beds, Boivvden, 

 Jamaica, (^y^-'j 'ek<.,'Bi^: D./i^e^B). 



