INSTITUTE OF SCIENCE, PHILADELPHIA. 



57 



ROCKS OF HOMOSASSA RIVER. A good section of the rock of the 

 region is exposed at Wheeler's, on the left bank of the stream, about 

 one mile above its mouth. It is a tough limestone, rising at different 

 stages of the water probably two or three feet above its surface at the 

 time of our visit about one and a-half or two feet and exhibiting numer- 

 ous holes, fissures and sinks that have been irregularly worn into it by 

 the water. The surface appears to be practically horizontal, exhibiting 

 no measurable dip. The rock is densely charged with foraminiferal 

 remains, all, as far as I have been able to determine, referable to the 

 Miliolidae, or to the group of the imperforate Foraminifera, as distinguished 

 from the Foraminifera Perforata, which, in the rock-masses further to the 

 south, usurp their place. I propose to designate this formation, repre- 

 senting one of the four distinct types of foraminiferal rock found in the 

 State, the " Miliolite Limestone " a member, doubtless, of the Upper 

 Eocene or Oligocene series, more likely the latter. Unfortunately, the 

 absence of distinctive molluscan remains in the rock rendered the 

 determination of its absolute age a little uncertain, but its close proximity 

 to the unequivocal members of the Oligocene rocks of the Cheeshowiska 

 River, a few miles to the south, leaves little room for doubt as to their 

 near equivalence. 



The genera of Foraminifera recognized as occurring in the Miliolite 

 Limestone are : 



Biloculina, Quinqueloculina, 



Triloculina, Sphieroidina. 



Another, and less compact, limestone, not unlikely belonging to the 

 same series as the last, is found in the immediate neighborhood of 

 Wheeler's. I examined large blocks of the rock that had been taken 

 from a well-digging, but the numerous fossil impressions contained 

 therein, mainly of bivalves, were so obscure or ill-defined as to permit 

 of no satisfactory results being arrived at from their partial determination. 



ROCKS OF THE CHEESHOWISKA RIVER. These are exposed nearest to 

 the sea on John's Island, at the entrance to the river, where a 

 yellowish, spongy limestone, containing numerous molluscan remains 

 and a few tests of the foraminiferal genus Orbitoides, appears on the 

 ocean front at low-water. The main-rock, which is of Oligocene age, is 

 bordered by, or incased in, a rock (limestone) of newer formation (Post- 

 Pliocene), in which the remains of marine organisms are freely intermingled 

 with those of a fresh-water type, such as Vivipara, Ampullaria, etc., 

 represented by species living at the present day. The re-formation of the 

 old limestone is thus made evident, but there can be no question, seeing 



