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I187 



TERTIARY FAUNA OF FLORIDA 



Diplodonta Leana Dall. 

 Psammocola lucinoidcs H. C. Lea, Trans. Am. Phil. Soc, 2d Ser., ix., p. 239, pi. 34, fig. 16, 



1845- 

 Not Diflodonta lucinoidcs Desh. (as Venus), Coq, Fos. de Paris, i., p. 146, pi. 23, figs. 



12-13, 1824. 



Miocene of Petersburg, Virginia ; Lea and Burns. 



This resembles D. shilohcnsis Dall, but is thinner, less inflated, with the 

 lower posterior margin more prominently rounded. D. caloosacnsis when adult 

 is much larger, and the young, when of the same length as D. Leana, are of a 

 rounded triangular form, conspicuously diiiferent from the regularly subovate 

 outline of D. Leana. D. imcleif orinis is a smaller, more cup-like shell with 

 proportionately more prominent beaks. 



Diplodonta punctata Say. 



Amphidesma punctata Say, Journ. Acad. Nat. Sci. Pliila., i., p. 308, 1822. 



Lucina venezuelensis Dunker, Zeitschr. Mai., v., p. 184, 1848. 



Lucina janeirensis Reeve, Conch. Icon. Lucina, pi. 8, fig. 43, June, 1850. 



Lucina subglobosa C. B. Adams, Proc. Boston Soc. Nat. Hist., ii., p. 298, 1847 (name 



only). 

 Diplodonta braziliensis Mittre, Journ. de Conchyl., i., p. 240, pi. xii., figs. 7-9, Aug., 1850 



(not Lucina brazilicnsis Phil.). 

 Diplodonta venezuelensis Dunker, Novit. Conch. Moll. Mar., p. 3, pi. iv., figs. 7-9, 1858; 



Dall, Bull. Mus. Comp. ZooL, ix., p. 136, 1881. 

 fDiplodonta orbella Gabb, Journ. Acad. Nat. Sci. Phila., 2d Ser., viii., p. 376, 1881 ; not 



of Gould. 

 Mysia pcllucida Heilprin, The Bermuda Ids., pp. 179, 190, pi. 17, fig. 3, Oct., 1889. 



Pliocene of Costa Rica ? Gabb ; Pleistocene of South Carolina and Florida, 

 Burns and Dall ; living from Cape Hatteras, North Carolina, south to Rio 

 Janeiro, and at Bermuda. 



This species is easily distinguished by its squarish orbicular form with 

 somewhat attenuated anterior end, and especially by the microscopic sculpture, 

 which exhibits short radiating striulse, minutely punctate where well developed, 

 and succeeding one another over a large part of the surface. This style of 

 sculpture appears to be peculiar to this particular species, which thus tends to 

 bridge the gap between Diplodonta proper and Phlyctiderma. It is not equally 

 well shown, however, on all specimens. 



