ijllill^ 



CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 31 



One of the most abundant fossils occurring in this bed is the Lignitic species, 

 Ostrea thirsce. The other species also, although mostly new, show a strong 

 relationship to the Lignitic fauna of the Gulf coast of the United States. 



In the judgment of Professor Harris this Soldado horizon is about equivalent 

 to the Nanafalayan of Alabama. 



COMPARISON OF THE STRATIGRAPHIC EVIDENCE FURNISHED BY THE 

 FORAMINIFERA AND THE MOLLUSCA. 



Dr. Rufus Mather Bagg most kindly examined the Foraminifera associated 

 with the molluscan fossils found on Soldado and Farallon Rocks. He was asked 

 particularly to express an opinion as to the geological ages of the deposits in 

 which they were found. Dr. Bagg writes: 1 "The Orbitoidal rock marked bed 

 No. 6, Soldado Rock, is Eocene. I am not sure just what horizon but I note 

 Orbitoidespapyracea (Boubee); Orbitoides aspera Gumbel (O.faujasii); and prob- 

 ably 0. mantelli 2 though I have not access to the literature on the subject. . . . 

 The Soldado bed No. 6 shows a few scattered forms of a typical Cretaceous and 

 early Eocene type which I have never come upon before, namely Tinoporus 

 vesicularis, and the more numerous allied species T. baculatus. Tinoporus* while 

 Cretaceous, is equally developed in the Lower Eocene, where I place your 

 rock. 



"The specimen from Farallon Rock is exceedingly interesting, and the entire 

 mass seems to be filled with Operculina complanata (Defrance) and is undoubt- 

 edly Eocene. It is not usual for this species to assume the role of the Eocene 

 Nummulitic or Orbitoidal rock types, and I am glad to identify this interesting 

 Foraminiferum, so characteristic of the early Tertiary formation. 



"The argillaceous shale from the Godineau River, Trinidad, was insoluble 

 in the caustic alkalies . . . but I am inclined to think it is of Miocene age, since 

 it is rich in diatoms and it has the rather typical Miocene genus Coscinodiscus 

 and a Pyxidicula. I sent a small fragment of this to Dr. Edwards of New York, 

 but he said he could not make a slide of it that was of any help in identifying the 

 diatoms." 



It is interesting to compare these conclusions of Dr. Bagg with those based 

 on the molluscan fauna by the writer, especially as they were reached wholly 

 independently. 



The evidence furnished by both Foraminifera and Mollusca as to the age of 

 the No. 6 bed on Soldado Rock point definitely to Lower Eocene. 



The Farallon Rock Foraminifera are, however, also referred by Dr. Bagg to 

 the Eocene. This bed is apparently an outlier off shore in the Gulf of Paria of 

 the San Fernando bed, and the latter contains a molluscan fauna of a decidedly 

 Oligocene aspect. There seems to be no question that the San Fernando and 



1 Letter dated January 30, 1912. 



2 According to Dr. Dall, the West Indian form of mantelli is 0. forbesii. 



8 For illustrations see Carpenter's Introduction to the Foraminifera, Plate XV, Figs. 1, 9. 



