hill: geology of Jamaica. 151 



Guppy has described 250 species of "Tertiary fossils of the "West 

 Indian region " without giving definite localities or horizons, but we 

 have reason for believing that a large majority of these come from the 

 Bowden beds. Dall has recently described ^ forty-eight additional 

 species from the " Oligocene of Jamaica," which are all from the 

 Bowden locality. 



No detailed list of the molluscan fauna of Bowden as a whole has 

 been made,^ although such a catalogue would be most important and 

 valuable, for with it the discussion of all great questions concerning the 

 West Indian later Tertiary paleontology would be made intelligible, 

 while now this subject is in a stage of mist and chaos. Dr. Dall has iu 

 his hands the material for such a catalogue, and it is sincerely hoped 

 that he will make one at an early day. It is a well known fact that a 

 large percentage of these Bowden forms have persisted through later 

 times and are at present living in West Indian waters, and that de- 

 ductions concerning the Pliocene or Pleistocene age of the succeeding 

 beds can be made only on the percentage of many forms. Without a 

 census of the Bowden molluscan fauna, it must be evident that all such 

 deductions as have been or will be made concerning this fauna are 

 unstable. 



Dall correlates* this molluscan fauna with the " Chipola, Tampa, and 

 Chattahoochee horizons of Florida, corresponding to the Aquitanian of 

 France." He also notes the wide occurrence of this fauna in the An- 

 tilles, Trinidad, and Curagoa, and on the mainland of Panama. A large 

 percentage of these forms still exist in the adjacent seas and represent 

 the ancestral conditions of the present life. 



No traces of Pteropods were found in my examinations of any of the 

 rocks below the Bowden beds. In the latter numerous specimens of 

 small Pteropods about five millimeters in length appear. In these beds 

 there are also many specimens of a craniate shell attaining a diameter 

 of half a centimeter which may belong to this order. Bagg has kindly 

 identified the species as follows : Hyalaea gibbosa, Eang ; Hyalsea lim- 

 bata, d'Orb. ; Hyalfea (Diacria) vendryesiana, Guppy. 



The land and fresh water Mollusca of these beds stand out strong and 

 clear, thanks first to the admirable studies of Simpson.'* lie enumerates 



1 Proc. U. S. Nat. Mus., Vol. XIX. pp. 303-331, Washington, 1896. 



2 I have heard that G. F. Harris, British Museum, is now working on one. 

 8 Proc. U. S. Nat. Mus., Vol. XIX. p. 304, Washington, 1896. 



* Distribution of the Land and Fresh Water Mollusks of the West Indian Kegion 

 and their Evidence with Regard to Past Changes of Land and Sea. By Charles 

 Torrey Simpson. Proc. U. S. Nat. Mus., Vol. XVIL pp. 423-450, Washington, 1894. 



