393 I'he Oligocene of the Southern United States 83 



Dr. Lea,* in 1833, expressed a doubt whether a single Amer- 

 ican species would prove stridlly analogous with a European form. 

 Nevertheless he made several comparisons. Dr. Bronn.f in 1848, 

 mentions a few American as synonyms of European species. 

 Prof. Heilprin, in 1879,:!: 1884II and 1887, § compared a consider- 

 able number of closel3^ allied or identical forms among the Eocene 

 and Miocene of the two continents. Under the Oligocene, he 

 takes up only Ostrea Geoj'giana Con., which, he suggests, may be 

 analogous with O. crassissima Lmk. , of Europe. As the Shell 

 Bluff beds containing O. Georgiana are now referred to the Eo- 

 cene, no identical forms would be left in his grouping under the 

 Oligocene. 



Dr. Otto Meyer,** in 1884, from a study of some 706 German 

 Tertiary shells and a number of American forms, found a few 

 identical species, which are quoted in Heilprin's article of 1887. 

 Dr. Dall,tt in his decription of the Florida Tertiary fauna, calls 

 attention to a number of species analogous with the European, 

 but the majority of these are Pliocene or Post Pliocene. 



Oligocene species. The identical or closely allied species in 

 the Oligocene of the two continents are but few. Among them 

 are the following: 



TRIFORIS PERVERSUS Linnd 



This species is cited by Spej'er (Lippe-Detmold, p. 21) from 

 the German Oligocene, and by Benoist (Cat., p. 340) and De- 

 grange-Touzin (Ee Thil) from the Gironde valley. Dr. Dall 

 {Trans. Wag. Free hist. Sci., iii, p. 264) regards CcritJmun 7710- 

 deshim, C. B. Adams (Contr. Conch., p. 117, Ap., 1850) as a 

 variety of Triforis perversus, and cites this variety from the Oli- 

 gocene of the Chipola beds. It is also found in the Caloosahatchie 



* Contr, to Geol., p. 19. 



t Index PalcEontographicus, 1848-9. 



XPvoc. Acad. Nat. Sci., Phila., 1879, pp. 217-225. 



WJour. Acad. Nat. Sci., Phila., 1884, pp. 104-112. 



§ Contr. Tert. Geol., 1887, pp. 83-101. 



**Proc. Acad. Nat. Sci., Phila., 1884. 



tt Trans. IVag. Free Inst. Sci., vol. 3. 



