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Genus ATSIITA Graj?. 

 ATRTI^A sp. inflet. 



The genus Atrlrig.. is representeil b^/ a sinp-le fragmentary 

 right valve. The ventral r.argln, apical and extreme posterior 

 portions are missiug, so that the outline is uncertain, although 

 it a -pears to be elongated and slender with the dorsal margin 

 straight and slis-htly refle3?:e5, Most of the external surface is 

 sculpture ' ''- relati"cli' coarse oblique ru.dulations upon v.hich 

 are superimposed finer oblique markings; but along the ventral 

 edge, \"hich may be some distance from the ventral margin, there are 

 indications of at least one longitudinal ridge. BecaTise of the' 

 character of the sculpture and the feeble convexity, this frag- 

 ment is belipved to re'oresent a di s'':inc t s-oecies. 



OcG_rrence. - loTj^^r Miocene; B^wden beds, 3,o\vden, Jamaica. 



