1911.] NATURAL SCIENCES OF PHILADELPHIA. 165 



SCAPHOPODA OF THE JAMAICAN OLIGOCENE AND COSTA RICAN PLIOCENE. 



BY HENRY A. PILSBRY. 



Extensive collections of the fossils of the Upper Oligocene beds at 

 Bowden, Jamaica, were made for the Academy some years ago by the 

 late Uselma C. Smith and Mr. Silas L. Schumo. While preparing a 

 monograph on the recent Scaphopoda for the Manual of Conchology 1 

 in 1897-8, the writer determined the species of these beds, and pre- 

 pared the following descriptions and figures. Through oversight they 

 were not published at that time. 



Of nine species in our collection from the Bowden bed, two are 

 represented by fragments too incomplete for characterization. Two 

 are identical with forms from the Oligocene of Santo Domingo, 2 but 

 the number of species common to the two beds may be increased when 

 the smaller species are collected in Santo Domingo. 



The occurrence of rich Oligocene faunas of strictly littoral and sub- 

 littoral fades at levels but little above the modern sea level, in both 

 Jamaica and Santo Domingo, indicates emphatically that there was 

 no such general and profound or total submergence of that area during 

 the upper Oligocene as has been assumed by Dr. Schuckert. 3 



It is, moreover, inconceivable to students of the land-snails of the 



West Indies that the peculiar special faunas of the several islands 



could have been evolved since the Oligocene. 



Dentalium costaricense n. sp. Fig. 3. 



D. dentate Gabb, Journ. Acad. Nat. Sci. Phila., n. ser., VIII, p. 369 (in part). 

 D. costaricense Pilsbry, Manual of Conchology, XVII, p. 254 (name only). 



Shell moderately curved, solid, moderately tapering. Surface 

 sculptured with numerous somewhat unequal longitudinal rounded 

 cords, separated by interstices as wide as themselves, with threads 

 in some of the intervals, about 28 cords at the larger end, not counting 

 the interposed threads; towards the smaller end alternate cords 

 become more prominent, especially on the concave side; there are 

 moderate, oblique growth-striae throughout. Aperture oblique, with 

 thin peristome. Both orifices circular. 



1 Manual of Conchology, vol. XVII. 



2 Scaphopoda of the Santo Domingo Oligocene, Proc. A. N. S. Phila. for 

 1897, pp. 465-476. 



3 Paleogeography of North America, plate 97. 



