Guppy — West Indian Geology. 499 



2. Upper Miocene. 



a. Cumana. 



b. Barhuda. 



c. Trinidad (1. Mornga Series: 2. Caroni Series). 



d. Jamaica (Vere, Bowden and Upper Clarendon Beds). 



e. San Domingo (Nivaje shale, etc). 

 /. Anguilla. 



g. Antigua (Chert formation : Conglomerate beds). 

 h. Barbados (Scotland formation). 



3. Lower Miocene. 



a. Trinidad (Manzanilla Beds). 



b. Trinidad (San Fernando Beds). 



c. (.*') Barbados (Nucula-rock.) 



It will be noticed that I have inserted the name of Barbuda in the 

 list of Upper Miocene localities given above. Having recently 

 examined a small collection of fossils from that islaad, I have deter- 

 mined the following species from it : — 



OUva cylindrical Sow. Bulla striata, Brug. 



Nassa soUdula, Guppy. Tellina biplicata, Conrad. 



All these species occur in the Miocene ; and thus Dr. Duncan's 

 conclusion, as to the existence of the Middle Tertiary in that island, 

 is now confirmed by the discovery of these moUusca. 



5. Mr. Jeffreys, in his paper on " Dredging among the Hebrides ^ 

 notices that the diffusion of univalves is slower than that of bivalves. 

 This fact may help us to explain why there should be comparatively 

 so large a proportion of bivalves common to the Middle Tertiaries of 

 the United States, and the West-Indies. The species . of mollusca I 

 have ascertained to occur in both these areas are as follow : — 



Univalves. — Petaloconchus sculpturatus, Lea. 

 Uentalium mississipense, Conrad. 

 Latirus infundibulum, Lam. 

 Bivalves. — Artemis acetabulum, Conrad. 

 Tellina biplicata, Conrad. 

 Becten Mortoni, Conrad. 



„ comparilis, Tuomey and Holmes. 

 Lucina pennsylvanica, Linn. 

 Ostrea virginica, Gruel. 

 Teredo fistula, Lea. 

 Chama arcinella, Lam. 



Thus we have another fact pointing to the greater facilities which 

 must have existed for migration between the European and Caribean 

 Middle Tertiary seas than between the latter and North America. 

 For, although but few Gasteropoda are common to the European and 

 the Caribean Miocene, yet very many are closely allied, which is not 

 the case with those of America. Further, all those species of 

 mollusca, which Conrad and other authors find to be common to 

 both continents, are bivalves. And there are as many bivalves 

 common to the European and West-Indian Miocene as there are to 

 the latter, and that of the United States. 



1 Ana. and Mag. N.H., 3 ser., vol. 18, p. 387, (Nov. 1866). 



