12 BULLETIN" 90, UNITED STATES NATIONAL MUSEUM. 



here what has been repeatedly stated before by the writer, but appar- 

 ently not clearly understood by them. 



The Miocene to which reference is made in all my discussions of 

 this subject is the Chesapeake Miocene of America, which has been 

 shown by me^ to have as a European analogue the Helvetian of 

 northern Europe, Belgium, north Germany, and Denmark rather 

 than the Molasse of Switzerland, the warm-water Miocene of south- 

 ern France, and the Vienna Basin. 



This Chesapeake Miocene has been recognized on the North Ameri- 

 can continent as far south as Lake Worth and in Key Vaca, Florida, 

 and Galveston, Texas, in all these cases from artesian borings. Far- 

 ther south than this we have no evidence of its existence. In most 

 cases where exploration has been made, as at Panama and the Te- 

 huantepec Isthmus, faunas determined as Pliocene immediately suc- 

 ceed those of the upper Oligocene, leading to the inference that the 

 1 and stood higher in the Middle American region during the Miocene 

 than during the periods preceding or following that epoch. Whether 

 the subtropical Mediterranean Miocene has any analogue above the 

 sea in this general region, including the Antilles, is doubtful. If it 

 exists it may possibly be found in the beds of Santo Domingo or 

 Costa Rica, where the problems of the stratigraphical relations of 

 reported fossils still remain to be elucidated. 



The Jacksonville formation is agreed to represent the typical Mio- 

 cene of the Chesapeake Group in eastern Florida. In the western part 

 of the State, where it has been given the name of the Choctawhatchee 

 marl, it contains the same fossils in a better state of preservation. 



This summary of the report of Messrs. Matson and Clapp is nec- 

 essarily so brief as to do scant justice to the large amount of addi- 

 tional detail which it brings to our knowledge and the profuse eluci- 

 dation of the geology which it contains. 



The latest publication bearing on the present monograph which 

 has been considered by the writer is the monumental volume by Dr. 

 Bailey Willis, entitled " Index to the Stratigraphy of North Amer- 

 ica." ^ This portion " has been compiled by T. W. Vaughan from 

 the literature and from the unpublished results of G. C. Matson and 

 E. W. Berry in western Florida," etc. The portion relating to the 

 beds immediately adjacent, above or below the Orthaulax zone, is 

 quoted from the second annual report of the Florida Geological 

 Survey by Matson and Clapp, above referred to. 



Doctor Vaughan^ adds the following paragraph of general 

 interest : 



Seclimeuts of upper Oligocene age extend westward from western Florida to 

 the Mississippi River. The Apalachicola Group or marine upper Oligocene 



1 Maryland Geol. Survey, Miocene, 1904, pp. cxxxix-clv. 



- U. S. Geological Survey, Professional Paper No. 71, 1912, pp. 731-745. 



3 Idem., pp. 744-745. 



