144 bulletin: museum of comparative zoology. 



Cambridge, Montpelier, and Moneague Eocene formations. They are 

 missing in all subsequent strata. 



It is also now apparent that Dall's recent statement,^ based upon 

 Guppy's material from alleged Miocene beds (Oligocene), to the effect 

 that " Orbitoides mantelli has not been found in the West Indian species," 

 is incorrect, and we must accept the occurrence of this species as iden- 

 tified by those eminent authorities, T. Rupert Jones ^ and E. M. Bagg. 



Concerning the other Foraminifera of the Cretaceous and Eocene strata 

 it can be said that Alveolina is a genus which elsewhere " begins in tlie 

 Cenomanian, continues in extraordinary profusion, and becomes a most 

 important rock builder in the Eocene ^ of the Paris Basin, Libyan Desert, 

 and Greece, is also reported by Jones in " Alveolina limestone " from 

 Crofts in the northeast corner of Clarendon, — a locality of the White 

 Limestone which we have not had the opportunity of visiting. 



The Orbitoides, ISTummulinae, Alveolina, Operculina, and Globigerinae 

 are Foraminifera which have been found only in the Blue Mountains, 

 Montpelier, and Cambridge beds of the Cambridge section. These 

 genera, with the exception of Globigerina, which ranges extensively 

 through geologic time, from the early Mesozoic to the present, have 

 their typical and highest development elsewhere in the Vicksburg stage 

 of the Eocene Tertiary. In accordance with Dall's usage, the Vicks- 

 burg beds, to which the Montpelier beds are undoubtedly equivalent, 

 are now considered the base of the Oligocene. When we consider the 

 stratigraphic evidence concerning the containing formations, there is no 

 reason to believe that their occurrence in Jamaica is later than in this 

 epoch. 



The Mid-Tertiary Antillean revolution, with its mountain making, 

 expansion of land areas, and rearrangement of barriers and enclosures, 

 which closely followed after the Montpelier subsidence, seriously affected 

 the conditions of life and produced changes of environment affecting 

 the molluscan and other faunas of the whole Tropical American region. 

 After this revolution, the littoral mollusca, as it next appears in the 

 Bowden formation, presents new and distinct facies, characterized by the 

 appearance in Jamaican waters of species which also occur on the con- 

 tinental borders, many of which are still living. This fauna constitutes 

 the chief bench mark in the whole system of Jamaican Neo-Tertiaries, 

 just as the Cambridge does for the Eo-Tertiaries. 



1 Proc. U. S. Nat. Mus., 1896, p. 329. 



2 The Geologist, London, 1804, Vol. VIL pp. 10.3-105. 



8 Eastman's "Text Book of raleontology," by Karl A. von Zittell, London, 1896, 

 p. 26. 



