- 38 - 



teeth small, numerous, tminterrapted ; inner margin smooth except 

 for a few, inconsoiouous crenulations on the posterior end. 



This s"oecies, whieh oomes up to the Hecent virtually uaiohang- 

 is represented bj' several small valves. The largest has the fol- 

 lowing di :ensions,- length, 18 mm.; rnaxi .um altitude, 8.5 mm.; semi- 

 diameter, 5.8 mm, 



Gabb's Santo Domingian specimens labelled A. imbrioata Brug. are 

 typical umbonata, but amorg his Oosta Rican Pliocene inbricata are 

 some A. ( Jalloaroa) oanclida Gmelin. 



Occurrence .- Upper Oligocene.- Tampa silex beds, Florida 

 (Dall, 1898, 1915). Chipola marl, Florida (Dall, 1898). Oak 

 Grove sand, Florida (Dall, 1G98). Santo Domingo (Gabb, 1873). 

 La?er Eiocene; Bowden beds, Bov/den, . Janiaica. 



Pliocene.- Limon, Oosta ?.ica (Gabb, 1881). 



Pleistocene.- Florida Keys and iintilles (Dall, 1898). 



Recent.- Fstteras to southern Brazil, throughout the Antilles 

 and east to Bermuda in less than 50 fathoms. 



