FREE INSTITUTE OF SCIENCE 



TERTIARY FAUNA OF FLORIDA 



seems to the writer inadvisable. Happily, here and there, even with our present 

 most imperfect knowledge of the strata concerned, we have hints which enable 

 us to make approximate correlations. Such are the occurrence of character- 

 istic Chipola species at Roberts, Escambia County, Alabama, of plants similar 

 to those occurring above the Chipola at Alum Bluff, in the " Hattiesburg 

 phase" of the " Grand Gulf," and the presence of upper Miocene or lower 

 Pliocene brackish-water species near Vernal, Greene County, Mississippi, at 

 Shell Bluff on the Pascagoula River, later rediscovered in artesian well dig- 

 gings at Biloxi, Mississippi, and Mobile, Alabama. These clays were named 

 by Mr. L. C. Johnson, of the Alabama State Geological Survey, the " Pasca- 

 goula formation," and his conclusion in regard to them * was that it was repre- 

 sented at Alum Bluff', Florida, by the uppermost (Chesapeake) Miocene of the 

 latter locality. The species found in the clays at the typical Pascagoula locality 

 were Ostrea virginica, Rangia Jolinsoni, Miilinia lateralis, and fragments of 

 a Hydrohia which was described from the Mobile well as H. mobiliana. The 

 borings at or near Mobile have, according to Mr. Aldrich, furnished about ten 

 other species, mostly new and of brackish-water habit. According to Messrs. 

 Smith and Aldrich, an extension of borings in the Bascom Well, Mobile, Ala- 

 bama, to a depth of fifteen hundred to fifteen hundred and fifty feet brought 

 up, as might have been predicted, fossils of the Oak Grove horizon, the eight 

 hundred and fifty feet corresponding to the section of the lower part of the 

 Pascagoula, the whole of the Chesapeake Miocene, and the Oak Grove sands. 

 Of the twelve molluscan species identified from this depth one is known from 

 the Tampa silex beds, three from the Chipola, four from Oak Grove, three 

 range from Chipola or Chesapeake to recent, one is upper Miocene, and one 

 only known from Pliocene to recent. As only too often happens with such 

 borings, unless supervised by an expert, there is probably some mixture here, 

 but, on the whole, the list points to the base of the Oak Grove sands as the 

 probable horizon finally reached. In the communication to " Science" from 

 which I gather the above data f Messrs. Smith and Aldrich express the opinion 

 that the " Grand Gulf" must be " either Pliocene or more recent," and perhaps 

 " Post-Tertiary," while the Pascagoula " will eventually turn out to be Plio- 

 cene." In a subsequent communication to " Science" X I pointed out that the 

 confusion into which the subject had fallen is removed by recognizing the 



* Report on the Coastal Plain of Alabama, p. 97, 1894. 

 t Science, N. S., xvi., p. 835-7, Nov. 21, 1902. 

 + N. S., xvi., pp. 946-7, Dec. 12, 1902. 



