- 131 - 



A* lienosa Say (1) of the same size has a similar appearance, hut 

 is more evenly rotmded anteriorly and has a slightly more arouate 

 base, more ntuneroiis and flatter rihs which have a more definite 

 median sulcus and also a secondary sulc-as on either side and are 

 more obviously and finely nodulated, '■'■^le recent 7/est Indian A. 

 secticostata Heeve (2) also is more completely rounded anteriorly 



(1). Am. Oonch., pi. 36, fig. 1, i;:30. 



(2). Oonch. Icon., Ar^a, f i^- . 38, 1844. (= A. fori dam Oonrad, 1^69) 



and has vvlder interspaces. 



Occurrence .- Uprier Oligocene.- Santo -^omingo fSowerby, 1S50; 

 Gabb, 1873; Guppy, 1874, 1876) TGums-.na, Venezuela (Guppy, 1874) 

 ?Gatun formation, Panama (Toula, 1908). lower Miocene : Bowden 

 beds, Bowden, Jamaica. 



