46 Bulletin 15 356 



of the rock. Underground drainage and its attendent results, 

 such as sink holes, the disappearance of surface rivers, temporary 

 lakes and natural bridges, are characfteristic of the limestone areas. 

 The fauna of the Orbitoides rock comprises many of the char- 

 a(fleristic Vicksburg species such as Orbitoides mmitelli, Pe5ie.n 

 poidsoni and P. per'planus. As in the Gulf States, a large part of 

 this limestone is formed wholly of the remains of Orbitoides. 



Ocala 7iumimditic limestone. In the vicinity of Ocala, a 5'el- 

 low, friable limestone, containing nummulites, rests upon the 

 Orbitoides rock. Quarries at Ocala have exposed some twenty 

 feet of the nummulitic limestone without reaching the base. The 

 area of surface exposure is limited, extending from Ocala almost 

 to the coast. These beds were first described by Prof. John 

 Ive Conte.* He writes, "The whole of this portion of the penin- 

 sula appears to have been originally composed of a mixture of 

 sand and shell limestone, probably of the Eocene period. The 

 limestone comes to the surface almost everywhere; in some cases 

 it is composed of nearly pure carbonate of lime ,in others silicifi- 

 cation has taken place. But, in all cases where its structure can 

 be made out, it consists of a mass of conglomerate shell." 



T. A. Conrad, t in 1865, identified Globulus alveatus Con., 

 Venericardia p7'ima Con. and Dosiniopsis alta Con. from specimens 

 of Ocala limestone. He remarks that these are all Eocene species 

 of California, Maryland and New Jersey, and refers the Ocala 

 rock to the period of the Shark River matl of New Jersey. 

 The fauna is now found also to include a number of species occur- 

 ring in the Tampa and Chipola beds, but a greater number are 

 common to the Orbitoides limestone of which Ocala is a slightly 

 later phase. The Ocala limestone was first distinguished from 

 the Orbitoides rock by Prof. Heilprin. In 1862, masses of rock 

 containing foraminiferal remains were found by Mr. Willcox on 

 the Cheeshowiska River. The species was identified b}^ Prof. 

 Heilprin as a true nummulite, the first of the genus found in 



* Optical Phenomena of the Silver Spring, Amer. Jour. Set., 2nd ser., 

 vol. 31, p. II. 



■fProc. Acad. Nat. Set., Phila., 1865, p. 184. 



