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TERTIARY FAUNA OF FLORIDA 



Carolia CWakuUina) floridana Dall. 

 Plate 24, Figures 5, 6, (>b, 7, "] b. 

 C. {WakuUind) floridana Dall, Proc. U. S. Nat. Mus., xviii., p. 21, 1895. 



From the Oligocene of Florida in the Sopchoppy limestone on the 

 banks of Deep Creek near the Sopchoppy River, Section 13, Township 4, 

 Range 3, Wakulla County, Florida; collected by L. C. Johnson, of the United 

 States Geological Survey; also in the " Fuller's earth" bed by Dr. D. T. Day, 

 at Quincy, Florida. 



Shell thin, not sculptured, nacreous, suborbicular, and adherent, some- 

 what irregular ; tight valve flattened or concave, especially at the umbo ; left 

 valve convex with a moderately prominent umbo near the cardinal margin ; 

 hinge-margin variable, but always with a transverse flattish area arched in the 

 middle over the attachment of the internal ligament; exterior irregularly im- 

 bricated by the scaly nacreous layers ; interior smooth, with a large subcentral 

 nearly orbicular adductor scar ; right valve with the minute sealed byssal 

 foramen under the 'middle of the chondropliore connected by a soldered 

 linear suture with the upper anterior margin of the valve; chondrophore 

 rounded triangular, broad, radiately rugose above, recurved as a thin lamina 

 from the umbo in fully adult specimens (see figure), rather closely sessile and 

 fitting into the umbonal cavity of the opposite or convex valve; left valve 

 with the ligamentary attachment broadly triangular, marginated by a thin 

 lamellar deposit of shell substance on each side and arched over by the 

 elevated portion of the cardinal area. There is no trace of a scar correspond- 

 ing to the byssal muscle of youth in adult specimens. Antero-posterior 

 diameter 1 10, dorso-ventral height 1 10, maximum thickness of the closed 

 valves 9 mm. 



This fine shell, curiously enough, is, so far as known, the only species 

 in the Sopchoppy limestone which retains its shell-structure, all the other 

 mollusks, so far as observed, being represented only by their impressions in 

 the soft limestone. It is interesting to find an Egyptian type in our southern 

 fauna, though the only relation between them is, in the writer's opinion, that 

 which both bear to the Anoniiidce which preceded them, and the analogous 

 recent forms which have succeeded to them. The characters upon which 

 Carolia is based are purely dynamic and might be expected to occur in a long 

 succession of Anomiidce of any region, the several Carolias having no genetic 

 connection with each other, as such, any more than the Oregonian Batissa 

 has with those of other continents now living. 



