[Annals N, Y. Acad. Sci., Vol. XXVII, pp. 23-29. 28 January, 1916] 



NEW SIEEmAK PEOM THE TEETIARY OF PORTO RICO, 

 WEST INDIES 1 



By W. D. Mattheav 



{Presented hefore the Academy, S November, 1915) 



CONTENTS 



Page 



Introduction 23 



Description of species 25 



Diagnosis 25 



Probable affinities 26 



Place of origin of the Dugongs 27 



Molar-premolar formula in Sirenians 28 



Bibliography 29 



Introduction" 



Two specimens of fossil mammals were secured by Dr. Chester A. Reeds 

 from the Tertiary limestones of Porto Rico while on the natural history 

 survey of that island undertaken by the Academy. One consists of a 

 lower jaw and two vertebrae, the other of a few incomplete ribs. The 

 second specimen is probably sirenian but not further identifiable. The 

 lower jaw, however, is nearly complete, with the molar teeth preserved 

 and alveoli of the premolars, and is of considerable interest. 



Tertiar}'' mammals have been practically unknown from the West 

 Indies. The only one recorded in scientific literature, so far as I know, 

 is represented by the skull and jaws from so-called Eocene of Jamaica, 

 described many years ago by Owen under the name of Prorastomus sire- 

 noides. It is also a sirenian, of a more primitive and generalized type. In 

 the March, 1914, number of the magazine "Re vista de las Antillas," 

 Senor ISTarciso Rabell Cabrero has published photographs of two mammal 

 bones from the Porto Rican Tertiary, a scapula and axis, and discussed 

 their possible affinities. He did not compare them with Sirenia, and nat- 

 urally found the relationship to terrestrial mammals very perplexing. 

 The scapula is characteristically sirenian, having the peculiar curvature 

 and backward extension of the blade clearly indicated and agreeing in 



1 Manuscript received hj the Editor 27 November, 1915. 



(23) 



