1866.] GFPPY WEST-INDIAN TERTIARIES. 589 



significance for this view that the corals of the Miocene beds of 

 Madeira are analogous to those existing in the Bed Sea*. 



The arguments which have induced me to favour the view that 

 there was some former connexion between the shores of the Atlantic, 

 do not entirely forbid the supposition that there may have been, 

 during some part of the Tertiary period, a connexion, by the way of 

 Panama, between the Atlantic and the Pacific. Mr. G. H. Saunders 

 discovered fossils of the Caribean Miocene on the isthmus in a cut- 

 ting of the Panama Eailwayf. Mr. Carrick Moore has given us a 

 list of West-Indian Miocene species related to Pacific forms J, all of 

 which, however, do not occur on the coast of America. There is also 

 a certain relationship between the recent faunas of the two sides of 

 the isthmus, as indicated by the following list of species either 

 identical or so nearly related as in some cases to present difiiculty in 

 their separation : — 



Cytherea Dione, West Indies and Mazatlan. 

 Purpura patula, West Indies and Panama. 

 Modiola Braziliensis, ,» „ 



• Mactra similis, „ ,, 



Purpura undata, West Indies = P. biserialis, Panama. 



sp., ,, ,, = P. nodosa, ,, 



Area illota, ,, ,, = A. Tayboyensis, „ 

 Adamsi, ,, ,, = A. soli da, ,, 



This is not intended as an exhaustive list ; but it is obvious 

 that there is nothing in it that would lead us to assume anything 

 more than a very partial migration. We do not find here that 

 strong chain of affinities which leads us from the Caribean through 

 the European Miocene to the shores of Madagascar and Ceylon. We 

 find, indeed, that those typical forms which are common to the 

 Caribean Miocene and the Indian seas do not occur on the west 

 coast of America. 



The general conclusions at which I have arrived may be shortly 

 stated as follows : — 



1. That the distribution of fossil and recent species shows it to be 

 highly improbable that the West-Indian Miocene forms reached the 

 localities where they occur as fossils by way of the Isthmus of Pa- 

 nama, or by an easterly route from Europe or from the Indian seas. 



2. That it is probable that there was during the early and middle 

 Tertiaries such a connexion between the shores of the Atlantic as 

 admitted of the migration of organized beings from one side to the 

 other, although the continents may not have been absolutely joined. 



In regard to the latter of these conclusions, it seems that the 

 evidence before us can scarcely yet justify any positive assumption 

 as to the particular direction in which the migration of species took 

 place, or whether the origin of the typical forms of the Miocene was 

 on the western or the eastern side of the Atlantic, or in the interme- 

 diate region. Another view is that there might have been an inter- 

 change of species ; but this would require a closer and more perma- 



* Lyell, ' Elements of Greology,' 6th ed. p. 668. 

 t Quart. Journ. Geol. Soc. vol. ix. p. 132. 

 t Ibid. vol. ix. p. 131. 



