TRANSACTIONS OF WAGNER 

 1556 



TERTIARY FAUNA OF FLORIDA 



which occupy a similar niche in the faunas succeeding the Eocene. As in all 

 oysters, this thin sculptured layer is easily decorticated, and to this fact is 

 largely due the confusion which has existed on the question of the geological 

 range of this species. 



THE OCALA LIMESTONE, OR NUMMULITIC ROCK 



OF HEILPRIN. 



This horizon was first discovered by Mr. Joseph Willcox and discriminated 

 from the Peninsular limestone by Professor Angelo Heilprin, who called atten- 

 tion to the contained nummulites, two of which he described as new. It is 

 best developed about the town of Ocala, where it forms the country rock and 

 has been quarried to a depth of twenty feet without reaching its contact with 

 the subjacent Peninsular limestone. The southernmost point where it has been 

 noticed is Pemberton's Ferry, Hernando County, but it has been observed at 

 many points north and west of Ocala and has been recognized at a point five 

 miles south of Jackson, Clarke County, Alabama, where specimens containing 

 the distinctive nummulites were collected by Mr. T. W. Vaughan, of the United 

 States Geological Survey. It seems probable that this limestone was continuous 

 in deposition with the upper part of the Peninsular limestone of Florida, which 

 is generally supposed to belong to the Vicksburgian, and the two are distin- 

 guishable only by their contained fauna, the nummulites, a great profusion of 

 other foraminifera, and a certain number of mollusks being characteristic of 

 the Ocala limestone. A detailed account of its distribution is given in Bulletin 

 84 of the United States Geological Survey, though, as in other cases, the geo- 

 logical conclusions of that work have been modified by later researches to some 

 extent. 



The rock at Ocala is a fine-grained, pale-yellow, calcareous sandrock, easily 

 disintegrated when fresh, but hardening somewhat under the influence of ex- 

 posure to the weather. Except in rare instances the molluscan fossils are only 

 represented by molds and internal casts, which are often very perfect, but diffi- 

 cult to get casts from, owing to the friability of the rock. The principal locality 

 for the material collected by Mr. Willcox is known as Richard's Quarry, and, 

 among other things, bones of a fossil cetacean, perhaps a species of Squalodon, 

 were embedded in the soft rock. 



The fauna of the limestone appears to be the same as that of a much silicified 

 country rock quarried at Martin, a railway station about ten miles north of 

 Ocala in Marion Countv. This rock on account of its hardness has been trans- 



