742 WILLIAM F. JONES 
Turritella planigyraita Guppy 
Natica (stigmaulas) sulcata Born 
Amauropsis guppyt gurabensis Maury 
Neretina (Smaragdia) viridemaris Maury 
Neretina sp. 
Astralium karlschmidti Maury 
Callisotoma grabaui Maury 
Melanella (Eulima) cercadica Maury 
Dentallinum dissimile Guppy 
Potamides caobensis Pillsbury 
Scapharca guayubinica Maury 
Scapharca henekent Maury 
Scapharca (Cunearca) willardaustent Maury 
Scapharca losguemadica Maury 
Scapharca hispaniolana Maury 
Pecten cereadica Maury 
Lucina chrysostoma Philippi 
Phacoides (Miltha) smithwoodwardii Maury 
Cardium (Trachycardium) tintinabularum 
Tellina islahispaniolae Maury 
Mytilopsis domingensis Recluz 
Corbula (Cuneocorbula) dominicensis Gabb 
Corbula (Cuneocorbula) caimitica Maury 
Euspamia sp. 
Madrapore sp. 
The Las Cahobes member of this series has resisted erosion to a 
greater extent than the members above or below it. Hence there 
is a generally well-defined valley or depression skirting the edge of the 
plain in its lower part which is underlain by beds of the lower or 
Thomonde division. The Las Cahobes beds stand above the 
general level of this plain and, where tilted, form hills parallel to its 
border (Fig. 7). Along the eastern and southern sides of the plain 
these hills are prominent and where the beds are nearly vertical 
sharp ridges are formed by the harder members, chiefly the con- 
glomerates. Pine trees grow in the central plain but are confined to 
the areas of Las Cahobes rocks. | 
The foregoing notes will explain why the division of the series 
was made. It may not stand from a paleontologic viewpoint. It 
will prove useful, however, in future work and makes delineation 
of structure fairly simple. 
