_ 1 - 



The present work offers s detailed study of the 

 pelecypods of the riahest mi'l-^ertiarj fauna -cnov.'n in the 

 Antillean re<?ion. It is believed to represent a horizon of 

 high importance in that interesj;ing area and if it is possible 

 to definitely correlste it virith the Tertiary section of the 

 Ooastal Plain of the United States a step of no small inporta,nee 

 will have oeen ta>en toward the solution of the many dispiited 

 issues of 'Vest Indian stratigraphy. 



The grouping of tlie general considerations uaider 

 three headings i'las the disadvajatage of postponing the express- 

 ion of the significance of certain features, but an obvious ad- 

 vantage lies in the segregation of elements and relations that 

 are salient from r^ifferent points of view. In the systematic 

 discussions •;revioiTSly described forms are redescribe . v.nenever 

 it is considered necessary, not only to remedy deficiencies in 

 the original diagnoses, but also in order to establish uniform- 

 ity in the employment of different terms. In the list of occur- 

 rences mider each species an attempt has been made to assign 

 each occurrence to the nroTc-r authority exce"ot in the c»se of 

 the geographic and bathjTiietric ranges of the .-cecent species, 

 which have been obtained from a catalo°-ue, conpiled by I'iss 

 Julia A. Gardner from vario":!S sources. 



