64 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



of its parts are occasionally recognized. In reports on the other parishes 

 it has been termed "White Limestone," and " Calcareous Marl" of St. 

 Thomas-in-the-Vale, Metcalfe, and St. Mary, and referred to the Cre- 

 taceous, Eocene, and Miocene ages. 



The term " Yellow Limestone " is peculiarly applicable to these beds, 

 but unfortunately this name was also applied, through the erroneous 

 correlation of Wall/ Etheridge,^ and others, to the beds of Oligocene 

 age at Bowden, as shown in the Introduction of this report. In view of 

 these facts, it is unwise to continue further the term "Yellow Lime- 

 stone" as a formation name for any of the Jamaican beds. 



The highest point at which the Cambridge beds are known to occur 

 is 3,000 feet, near Luidas Yale, St. Catherine Parish. 



There are several paleontologic and stratigraphic features of the 

 Cambridge beds which are peculiar, and will require more extensive 

 field work for final explanation. We have reason to believe that the 

 beds are not connected, but occur in broken patches, which, at least in 

 their lower portion, like the Cretaceous beds, represent sporadic colonies 

 of lime making organisms, which found temporary foothold at intervals 

 during a period of turbulent deposition generally unfavorable to a large 

 development of marginal life. These deductions are based upon the 

 fact that in no two localities are the sequence of sediments or associa- 

 tion of species identical, while in others the beds do not appear between 

 the Richmond and Montpelier. Furthermore, the fossiliferous horizons 

 of the Lower Cambridge are so like some of the Cretaceous that the 

 one has been frequently mistaken for the other. The mixture of Cre- 

 taceous Rudistes and Eocene corals and mollusca at Catadupa, as seen 

 by us, and of Orbitoides and Rudistes in Portland, as noted by Barrett,' 

 indicates a transgression of Cretaceous life into the Eocene, and further 

 denotes the anomalous nature of this formation. 



These beds, while showing sedimentary relations to the Richmond, 

 undoubtedly represent a transitional step in the deepening which later 

 produced the Montpelier formation. In some places it seems perfectly 

 conformable beneatli the latter, while again, as shown by Brown and 

 seen in several places by us, they are unconformable. These apparently 

 irreconcilable conditions can probably be explained upon the hypothesis 

 that the island was undergoing subsidence during the Cambridge epoch, 

 although parts of it were then dry land, which was still further covered 



1 Quart. Jour. Geol. Soc. London, Vol. XXI. p. 56. 



2 Jamaican lieports, p. 311. 



8 Quart. Jour. GeoL Soc. London, 1860, Vol. XVL pp. 324-326. 



