590 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jlllie 20, 



nent connexion of the two sides of the Atlantic. On the whole, the 

 balance of evidence appears to be in favour of the view that there 

 was migration from the western to the eastern side of the Atlantic. 

 In conclusionj I may observe that I have been unavoidably led to 

 support a modification of the Atlantis hypothesis provisionally, and 

 until it can be clearly shown what theory can best reconcile the 

 facts. It is to be hoped that our information relating to the Tertiary 

 formations will be increased by all who have it in their power to do 

 80 ; for principles may thus be made manifest which may hereafter 

 be applied to the study of the older formations. I readily admit 

 that I have by no means exhausted the analogies of the fossils treated 

 of in this paper. I fully believe that more relations will be esta- 

 blished between the fossil faunas of San Domingo and Jamaica and 

 Europe and the living fauna of the Indian seas than I have been 

 able to determine satisfactorily. I am aware of the shortcomings of 

 my papers in this and other respects ; but I trust that others may be 

 induced to carry out stiH further the comparisons I have attempted, 

 and to show their real import. It may be that I have fallen into 

 some errors ; but I hope that the true inferences may be drawn from 

 the facts. I believe that one of those inferences will be, that the 

 Miocene of the "West Indies must be included in the same great 

 period of time as that of Europe, and may therefore be considered, 

 in a geological sense, synchronous — though even in this instance the 

 doctrine of homotaxis may be so far true that neither the commence- 

 ment nor the termination of the Miocene period, as indicated by 

 organic types and limited by physical changes, may have been 

 simultaneous in the European and Caribean areas. 



EXPLANATION OF PLATE XXVI. 



{^Illustrative of West-Indian Tertiary Fossils.) 

 [The figures are all of the natural size, with the exception of fig. 19 «.] 

 Fig. 1. Cercomya ledcuformis. Manzanilla, Trinidad. 



2. Mactrinula macescens: 2a, hinge of left valye; 2d, hinge of 



right valve ; 2 c, exterior of left valve. Manzanilla, Trinidad. 



3. Area Trinitaria : 3 a, posterior view of the shell with the valves 



united ; 3 b, exterior of left valve. Manzanilla, Trinidad. 



4. Carditcm castum. Manzanilla, Trinidad. 



5. Arcafilicata. Manzanilla, Trinidad. 



6. Erycina tensa. Manzanilla, Trinidad. 



7. Ficula carbasea. Savanetta, Trinidad. 



8. Corbula vieta. Manzanilla, Trinidad. 



9. Ancillaria lamellata. Manzanilla, Trinidad. 



10. Sjpirorbis clymenioides. San Fernando, Trinidad. 



11. Nassa soUdula. Cumana. 



12. Turritella tornata. Cumana. 



13. Cytherea juncea. Cumana. 



14. Melanopsis cejyula. Cumana. 



15. Bosinia cyclica: 15a, exterior of right valve; 15 Z>, hinge of 

 / right valve. Manzanilla, Trinidad. 



16. Venus Walli. Manzanilla, Trinidad. 



17. Gryphcea athyroides. gan Fern.indo, Trinidad. 



18. Eanina porifera. San Fernando, Trinidad. 



19. Cisseis asteriscus: 19a, portion magnified; 19 b, the whole of 



the fossil, natural size. San Fernando, Trinidad. 



