224 BULLETI'N 103, UNITED STATES NATIONAL MUSEUM. 



The following is said as to the bearing of this fauna on a possible 

 post-Oligocene interoceanic connection: 



That there was interoceanic connection across parts of Central America during 

 upper Oligocene time and that this connection was terminated in Miocene time is 

 generally admitted. The extinction of Pacific faunal elements in the Gulf of Mexico, 

 the Caribbean Sea, and the Western Atlantic Ocean has been discussed and sum- 

 marized on page 366. Was there interoceanic connection during upper Miocene or 

 Pliocene time after the sharp differentiation of the Caribbean and Mexican Gulf 

 faunas from the Indo-Pacific faunas, thereby permitting interoceanic faunal migra- 

 tion? The discovery of a reef-coral fauna of purely Floridian and Caribbean facies at 

 the head of the Gulf of California strongly suggests, if it is not positive proof, that the 

 western Atlantic fauna extended from the Atlantic into the Pacific after the faunal 

 differentiation had taken place. It is well known that the living reef -coral fauna on 

 the Pacific side of Central America is depauperate in comparison with that on the 

 Atlantic side. Greater vigor may account for the dominance of the migrant fauna 

 over the Pacific fauna, which was finally suppressed, or geologic or other ecologic 

 conditions that are not yet understood may have excluded the Pacific fauna from the 

 head of the Gulf of California, while they permitted the migration of the Atlantic 

 fauna into that area. 



That the suggested interoceanic connection existed can scarcely be doubted. To 

 locate it, in the present state of meager knowledge of the areal and stratigraphic geology 

 of Central America, is not possible. Perhaps it was across the Isthmus of Tehuan te- 

 pee. The problem awaits future investigation. 



This fauna differs from the Miocene fauna of the La Cruz marl of 

 Cuba in the absence of genera at present living in the Indo-Pacific, 

 for instance, Stylophoraj Pocillopora, and Gonio'pora. As none of the 

 Indo-Pacific genera occurs in the Carrizo Creek fauna, and as only 

 genera of Atlantic affinities have been found there, it seems neces- 

 sary to infer that the fauna migrated from the Atlantic to the head 

 of the Gulf of California after the Indo-Pacific genera had become 

 extinct in the Atlantic. This would mean connection between the 

 Atlantic and the Gulf of California in very late Miocene or Pliocene 

 time. 



Attention should here be called to a statement for which I am 

 responsible. It is said in the report referred to below ^ that some 

 fossils obtained by Mr. William Palmer in a quarry in Calle Infanta, 

 Habana, may be of Pliocene age, although it is probable that they 

 are Pleistocene and that other limestone near Habana is perhaps of 

 Pliocene age. The material obtained by Mr. Palmer is very poor, 

 but some specimens are casts of the inside of the calice and the inter- 

 septal loculi of a large bilobate species of Antillia. The species more 

 probably is A. walli Duncan of the Bowden marl, but it might be 

 A. hilohata Duncan; another cast seems to represent a species of 

 Thysanus: while another is a species of SyzygophylUa, probably 

 S. dentata (Duncan). One specimen of Stephanocoenia intersepta 

 (Ellis and Solander) is identifiable. The material seems quite 

 clearly to represent either the Bowden or a somewhat higher horizon 



I Hayes, C. W., Vaughan, T. W., and Spencer, A. C, A geological reconnaissance of Cuba, p. 23, 1902. 



