226 CARLOTTA J. MAURY 
beds were found, I believe that three formations’ are represented, 
named from their characteristic fossils and given in ascending 
order: the Orthaulax inornatus, the A phera islacolonis, and the 
Sconsta laevigata formations. The Orthaulax horizon is approxi- 
mately equivalent to the Rupelian of Europe, ties up with the Tampa 
silex beds of Florida, and is Oligocene. The A phera horizon is the 
Upper Aquitanian of Europe, which is Lower Miocene, and is 
linked with the marls of the Chipola River, Florida. The Sconsia 
horizon is the Burdigalian of Europe, which is Middle Miocene and 
is synchronous with the Oak Grove sands and the cross-bedded 
Alum Bluff beds? of Florida. 
In closing the Oligocene with the Rupelian we agree with the 
European geologists. In this country custom varies, certain very 
prominent geologists continuing the Oligocene farther up because 
of the absence of any conclusive stratigraphic break. According to_ 
the latter view no Miocene is present in the Antilles, because it is 
thought that they were so highly elevated during that period that 
the materials deposited lie now out at sea. 
There seems, however, to the writer no necessity for postulating 
this great change of level, and the supposition that Oligocene time 
in the Antilles passed on into Miocene with continuous sedimenta- 
tion appears more probable. 
In connection with this question of Miocene versus Oligocene 
age, the discovery by Dr. Sellards, director of the Florida Survey, 
of Miocene vertebrates in Florida is illuminating. Our conclusions 
of the Miocene age of the Aphera formation in Santo Domingo 
and through it of the Alum Bluff cross-bedded sands and the 
sands of Oak Grove were made independently of Dr. Sellards’ 
results, with which they harmonize. 
Looking back to early Miocene times we may picture to our- 
selves an arm of the sea running east and west in the northern 
part of Santo Domingo and occupying what is now the valley of 
the Rio Yaqui. In the shallow waters was a rich molluscan fauna, 
solitary and compound corals were common, crabs of various 
genera and hermit crabs lurked about, bryozoa incrusted the 
t See Correlation Table, Bull. Amer. Pal., No. 30, 1917. 
2 See the writer’s drawn section, Bull Amer. Pal., No. 15 (1902), p. 57. 
