TRANSACTIONS OF WAGNER 



^ TERTIARY FAUNA OF FLORIDA 



The nepionic young of this species have very much the form of the adult 

 and are usually sculptured in much the same way. 



Dosinia (Dosinidia) liogona n. sp. 

 Plate 53, Figures 4, 7; Plate 54, Figure ii. 



Uppermost Oligocene at Oak Grove, Santa Rosa County, Florida; Burns. 



Shell much resembling the last, from which it differs by the less convex 

 posterior dorsal margin ; smooth or feebly sculptured beaks, sculpture rising 

 into a sharp, fine lamellae towards the ends of the shell, smaller adductor scars, 

 narrower hinge-plate, and different form of the nepionic j'oung. Height 45, 

 length 48, diameter 18 mm. 



The young shells are proportionately more elevated and shorter than the 

 adult and most of them are smooth or very sparsely concentrically grooved. 

 At first sight they would hardly be recognized as the same as the adults. The 

 posterior cardinals are elegantly crenate. In the adult the anterior left and 

 posterior right cardinals are grooved on the distal edge. 



Dosinia (Dosinidia) acetabulum Conrad. 

 Artemis acetabulum Conrad, Fos. Tert. Form., p. 20, pi. vi., fig. i, 1832; Fos. Medial 



Tert., p. 29, pi. xvi., fig. I, 1838. 

 Cytherea obovata Conrad, Journ. Acad. Nat. Sci. Phila., vii., p. 132, 1834 (young shell) ; 



Fos. Medial Tert., p. 14, pi. viii., fig. 4, 1838. 

 Dosinia acetabulum Conrad, Proc. Acad. Nat. Sci. Phila. for 1862, p. S7S. 1863; Meek, 



Checkl. Inv. Fos. Miocene, p. 10, 1864; Whitfield, Mio. Moll. N. J., p. 73, pi. xiii., 



fig. 2, 1895. 

 Dione obovata Conrad, Proc. Acad. Nat. Sci. Phila. for 1862, p. 575, 1863 (young shell) ; 



Meek, Mio. Checkl., p. 9, 1864. 

 Dosinia obovata Conrad, Am. Journ. Conch., vi., p. 77, 1870 (young shell) ; not of Bush, 



Trans. Conn. Acad. Sci., vi., p. 477, 1885 (= young of D. elegans Conrad). 



Miocene of New Jersey (artesian boring at Atlantic City) ; of Maryland, 

 at St. Mary's River (type locality), one mile north of Greensboro', near the 

 Choptank River, Calvert County, Plum Point, and Jones Wharf on the Pa- 

 tuxent River; of Virginia, at Grove Wharf and also near Smithfield on the 

 James River ; Coggins Point ; three miles above Yorktown, on the York River ; 

 Petersburg ; and in various places near Suffolk on the Nansemond, and in the 

 marl below the peat of the Great Dismal Swamp ; of Florida, in the Chesa- 

 peake Miocene horizon at Alum Bluft' on the Chattahoochee River (variety 

 obliqua). 



