433 Dominican Sections — Maury 17 



would be an exceedingly small fraction. There is an overwhelm- 

 ing proportion of extinct species. 



Relation of the Cercado Bluffs Faunas to the Bowden Fauna. — 

 The Bluff 1 fauna has the strongest bond with Bowden, but that 

 of Bluffs 2 and 3 is also related to Bowden, the respective re- 

 ciprocal percentages being 4.5, 3, 2.9. But the Bluff 1 fauna is 

 very unlike the mutually related Bluffs 2 and 3 faunas. 



The Bowden Fauna apparently not a unit. — It would seem 

 that several faunal zones are represented in the Bowden since it 

 has affinities with out dissimilar faunas. That it is not a unit is 

 suggested also by the description of the Bowden bed. Dall* says : 

 "The bed of marl which contains the rich fauna of Bowden occurs 

 in a calcareous gravel at the foot of Baker's Hill, Morant Bay, 

 Jamaica, about three feet above the sea." Such coarse material 

 as gravel suggests that the shells are not in their original situ, 

 which would have been farther off shore where finer material was 

 being deposited, and that they are an assemblage gathered by 

 currents and deposited in the calcareous gravels. 



For the above reasons the Bowden fauna is here tentatively 

 subdivided into upper, middle and lower horizons. This theory 

 must be tested by actual study in the field. 



Geology of the Rio Gurabo 



Oar explorations on Rio Gurabo were made in the vicinity 

 of Los Quemados, which is also one of Heneken's type localities. 

 The location of this hamlet is shown on the Sketch Map (12) 

 facing page 10 of Bulletin 29. A characteristic view of the river 

 bluffs are shown on Plate 3B of this bulletin. Actual superposi- 

 tion does not exist. The section is made up from successive 

 bluffs met with on ascending the river. The lettering is in de- 

 scending geological order. 



The dip at L,os Quemados is 16 feet in a hundred, N. 55 ° E. 



*Trans. Wagner Inst. Sci., vol. 3, pt. 6, p. 1583, 1903. 



