FREE INSTITUTE OF SCIENCE 



TERTIARY FAUNA OF FLORIDA 



Navicida aspcrsa Conr., Wailes, Agr. and Geo!. Mississippi, p. 289, pi. 14, fig. 5 (young 



shell), 1855. 

 Navicida aspera Conr., Proc. Acad. Nat. Sci. Phila., vii., p. 258, 1855 ; not Aral aspera 



Phil., Moll. Sicil., 1836. 



Upper Eocene (Jacksonian) near Claiborne, Alabama; Jackson, Missis- 

 sippi ; Cleve County, Arkansas ; and in the Lower Oligocene at Vicksburg, 

 Mississippi. 



This fine shell was separated from the true Arks by Conrad because in 

 the fully adult specimens the distal teeth are usually (though not invariably) 

 broken up into granular parts. This character occurs occasionally in individ- 

 uals or particular species in most groups of the genus Area and is too 

 mutable to be taken as a basis for a genus. The other Vicksburg species, 

 Barbatia mississippiensis Conr. {op. cit., 1848, p. 125, pi. 13, fig. 32), is distin- 

 guished from A. cuciilloidcs by its smaller size, finer sculpture, and the absence 

 of any radial ridges setting off a posterior area as in the latter species. 

 These ridges are very strong in the young, in which also the distal teeth are 

 entire, giving the young shell such a different aspect that Conrad described it 

 as a distinct species. Conrad described another Area, belonging to the 

 section Scaphaira, under the specific name of mississippiensis, in the same 

 paper (p. 125, pi. 13, figs. 1 1, 15), which appears to be that figured by Lesueur 

 in his Walnut Hills Fossils, pi. 5, fig. 8, 1829. This species may take the 

 name of A. [Seapharcci) Lcsiieiiri. The Barbatia mississippiensis was also well 

 figured by Lesueur on the same plate, figure 9. 



The Area 7'honiboidella Lea, Contr. Geol., p. 74, pi. 2, fig. 52, from the 

 Claibornian appears to be referable to Seapliarca. We have it also from 

 Lisbon, Alabama, the Eocene of Orangeburg, South Carolina, and according 

 to Haldeman from the Eocene of Virginia, the exact locality not being 

 recorded on the label. I suppose it must have been through an accidental 

 confusion that Cossmann came to identify B. ciiculloides with this species. 

 Omitting to notice that Conrad described his shell as two and a half inches 

 long, Gregorio {pp. cit., pi. xxiv., figs. 17-20) has figured a specimen of A. 

 rhomboidella tliree millimetres long as A. etteulloides Conrad. It seems 

 singular that he should not have noticed its practical identity with the figure 

 of Lea which he reproduces on the same plate (fig. 28). Cossmann has very 

 properly united the two, though he did not see that neither represented A. 

 cuculloides of Conrad. Gregorio's figure very fairly represents A. rliomboid- 

 ella, which, however, reaches a length of over twenty millimetres in the adult 



