62 
FLORIDA STATE GEOLOGICAL SURVEY. 
sular appears to have been originally composed of a mixture of sand and shell- 
limestone; probably of the Eocene period. The lime-rock comes to the surface 
almost everywhere; in some cases it is composed of nearly pure carbonate of 
lime; in others silicification, to a greater or less extent, has taken place by the 
displacement of the lime by silex. But in all cases where its structure can be 
made out, it consists of a mass of conglomerated shells. 
A later paper by Conrad 1 mentions some of the fossils found in 
the Ocala limestone, and correlates it with the Shark River Eocene of 
New Jersey. However, neither Prof. Re Conte nor Conrad made any 
special study of the Ocala limestone, and it remained for later work¬ 
ers to recognize its distinctive characteristics. 
The Ocala limestone was for a long time regarded as a part of 
the Vicksburg “limestone,” as it was then known; but it was later 
separated from the Vicksburg. It was in 1882 that Mr. Joseph Will- 
cox discovered a rock from the vicinity of Chassahowitzka River which 
he submitted to Heilprin 2 for identification. Heilprin recognized some 
of the fossils as nummulites, and to a new species belonging to this 
genus he gave the name Al, willcoxii. In 1886 Prof. Pleilprin 3 added 
another to the published list of localities where the nummulitic fauna 
is known to occur. This new determination was based upon the pres¬ 
ence of Nummulites floridanus which was obtained near Arredondo 
about six miles southwest of Gainesville. The specimens were col¬ 
lected by Prof. G. A. Wetherby and Mr. Joseph Willcox. 
In his paper on the Neocene of North America, Dr. Dali 4 mentions 
Prof. Heilprin's discovery of nummulitic rock in Florida and suggests 
the name Ocala limestone from the locality where it is best exposed. 
He states (p. 103) : 
Among the rocks which until recently were not discriminated . from the 
Orbitoides limestone, and which appear in central Florida directly and con¬ 
formably to overlie the latter, though no one has described their contact, is a 
yellowish friable rock containing many foraminifera, conspicuous among which 
are two species of nummulites, N. willcoxii and N. floridana Hp. This rock was 
first brought to notice by Mr. Joseph Willcox, and to Prof. Heilprin we owe a 
description of it which discriminates between it and the Vicksburg or Orbitoides 
rock. The rock was early recognized as Eocene, though not discriminated from 
the earlier beds. It is best displayed at Ocala, Florida, where it forms the 
country rock, and has been quarried to a depth of 20 feet without coming to 
the bottom of the beds. 
1 Conrad, T. A. Observations on American fossils with descriptions of two 
new species. Proc. Acad, of Natural Sciences, Philadelphia, 1865, p. 184. 
2 Heilprin, Angelo. Proc. Acad, of Nat. Sci., Philadelphia, 1882, pp. 189- 
193. Abstract of same, Am. Jour. Sci., 3rd ser., vol. xxiv, 1882, p. 294. 
3 Heilprin, Angelo. Notes on the Tertiary geology and paleontology of the 
southern United States. Am. Jour. Sci., 3rd series, vol. xxix, 1885, p. 69. 
4 Dali, Wm. H. Neocene of North America, U. S. Geol. Survey, Bull. 84, 
1892, pp. 103-104. 
