Maury — Porto Rican Tertiary Formation. 211 



species. Dr. Jonas concluded that the Arecibo lime- 

 stone "is both Upper Eocene and basal Oliogcene and 

 the Collazo shale is Upper Eocene." 



In 1917, after making an expedition to northwestern 

 Santo Domingo and working np the fossils collected 

 there, bnt without having seen any from Porto Rico, I 

 suggested that 9 "The Lares shales may go with the 

 Orthaulax zone of the Yaqui Valley, or perhaps with the 

 probably older Monte Cristi range. The limestones and 

 marls above the Lares shales perhaps correspond to our 

 Aphera and Sconsia formations." 



Dr. Vaughan of the U. S. Geological Survey, in his 1919 

 Correlation table of the Formations of the Canal Zone 

 with those of the West Indies and Central America, 10 

 gives but one horizon in Porto Rico, the Pepino forma- 

 tion, which he correlates with the Antigua formation, and 

 with the Lower Culebra of Panama. 



Conclusions based on a Study of the Fossil Mollusc a. 



All the preceding statements, or prophecies, regarding 

 the Tertiary stratigraphy of Porto Rico were chiefly 

 based on structural and physiographic relations, since 

 only a very preliminary study of the fossil faunas had 

 been made by any of the authors quoted. 



The American Museum of Natural History this Spring 

 requested me to make a critical study of the fossil mol- 

 lusca collected in Porto Rico by Dr. Reeds in 1915. The 

 discussion of the species will be published later, but it is 

 hoped that the following brief resume of the faunas and 

 their stratigraphic relationship may be deemed of 

 interest. 



I wish to thank Dr. Lucas, Director of the American 

 Museum, Dr. Hovey, Curator of the Geological Depart- 

 ment of the Museum, and Dr. Berkey, Geologist of the 

 Porto Rican Committee of the New York Academy of 

 Sciences, for their very kind permission to publish this 

 summary in advance. Acknowledgment is due likewise 

 to Dr. Reeds, Associate Curator of Invertebrate Paleon- 

 tology at the Museum, for helpful information regarding 

 field relations of the fossils studied. 



9 Bull. Amer. Paleontology, No. 30, p. 42. 



10 U. S. Nat. Mus., Bull. 103, opposite p. 595, 1919. 



