3 



The terms Eocene Miocene and Pliocene were originally 

 fixed by Lyell for the three great divisions of the tertiary strata 

 (see Principles of Geology 8th Ed. page 177 ; Elements 6th Ed. 

 page 187; and Student's Manual 1878 page 122) in accordance 

 with the percentage of recent species found in the formations 

 so designated. The percentage test though fundamentally a 

 useful one is not always free from difficulty in its application 

 to particular cases, and the West Indian miocene formation is 

 one of these cases. And this arises in some degree from the 

 fact that the proportion of recent species varies with each 

 observer. According to the list of names I give, amounting 

 to about a hundred species, there are not more than three 

 nr four .still existing species in our miocene beds, and even 

 these can easily be disposed of by giving them other names 

 which in most cases are ready to hand. When we come to 

 examine the shells we find a large number of them so near 

 to living species that it is only by critical tests that we can 

 separate them. Put the recent Analogues of these shells resolve 

 themselves into at least two categories, namely i° species 

 still living in the West Indies, and 2° species not now living 

 in the West Indies. And we find the resemblances of the 

 West Indian miocene shells are largely with Pacific and Indian 

 species rather than with West Indian species. Many again are 

 akin to European miocene species, so that when we compare 

 the fossil Fauna as a whole we find it very unlike the recent 

 West Indian Fauna. 



It may be noted as regards this collection that litoral 

 shells are absent from it. 



At different times I determined Fossils for Mr. Cunningham 

 Craig. Several of these had previously occurred to me in 

 the Caroni beds of Savaneta and are included in my list already 

 published. To complete the list of miocene fossils so far known 

 I add the names of such as were not given in that list to 

 those of the Springvale Fossils now recorded. These Fossils 



