136 bulletin: museum of comparative zoology. 



and Retreat, and the Catadupa and Cambridge outcrops were the only 

 IbssiUferous beds found. 



The statement of Barrett/ that Orbitoides "are Cretaceous fossils in 

 Jamaica," may possibly have been based upon a knowledge of the asso- 

 ciation of these forms with the Cretaceous Rudistes. 



In view of the facts presented, the writer finds it utterly impossible to 

 accept the " rolled " hypothesis, and he can see no way of avoiding the 

 positive conclusion that the Rudistean forms in the Cambridge beds rep- 

 resent a survival of Cretaceous types into the Lower Eocene. Such an 

 occurrence would in no manner be more anomalous than many other 

 facts connected with the peculiar insular faunas of late Cretaceous 

 and early Tertiary time in Jamaica, mentioned in this Report. Even 

 though the Rudistes should prove to be survivals, this Eocene fauna of 

 Catadupa as a whole shows anomalies comparable to those exhibited by 

 the Jerusalem beds, which mark it as peculiar. As a fauna, nothing 

 exactly analogous to it is known elsewhere. 



In view of the apparent mixture of Cretaceous and Eocene forms, 

 question might arise concerning the position of these beds in the geo- 

 logical column. Inasmuch as all the other genera are Eocene, it is our 

 opinion that it will be best to consider the beds of that age and to assume 

 that the Rudistean genera have transgressed into the Eocene. 



The fact that these beds are stratigraphically above the Richmond 

 beds is another consideration which leads us to the Eocene conclusion. 

 Inasmuch as the two species of coral from the latter (mentioned on page 

 126) attest the Eocene afiinities of the latter beds, the discovery of the 

 Cambridge formation gives a certainty to the existence of an Eocene 

 system in Jamaica, aggregating at least 1,500 feet in thickness, which, 

 in connection with the Montpelier beds to be described farther on, of 

 supposed Vicksburgian facies, shows the Eo-Tertiary beds of the island 

 to be fi\r more extensive than hitherto supposed. The paleontologic 

 peculiarities of the Richmond and Cambridge formations, analogous to 

 those of the preceding Cretaceous beds, are such as can only be ac- 

 counted for by geographic environment, and point to the early insularity 

 of the island through Eocene time. 



The relations of this fauna to other regions of the world is anomalous. 

 Its affinities in some respects seem more analogous to those of the south- 

 orn portions of I^uropo than to those of the United States, but we do not 

 dare at present to make positive conclusions except to agree with Moore 



^ Jamaican Keports, p. 7G. 



