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1231 



TERTIARY FAUNA OF FLORIDA u 



This large species, which Conrad at one time seems to have confounded 

 with the recent D. concentrica Born, of the Florida Keys, has two mutations 

 which are more or less connected by intermediate forms. The typical form is 

 somewhat transversely suborbicular and convex with the sculpture tending to 

 obsolescence on the middle of the disk. It is shown by very perfect topotypes 

 to have had in life a dark brown periostracum, very rarely preserved. 



The other extreme, which may be called variety obliqua (pi. liv., fig. .13), 

 is more compressed and higher, with the basal margin obliquely produced. 

 It is found with the others, and though at first I supposed it to be a distinct 

 species, I have been obliged to give up that idea. The nepionic young, less than 

 ten millimetres in height, from Suffolk, Virginia, were described by Conrad as 

 a species of Cytherea. They are often proportionately higher than the adults 

 and show the evanescent corrugations of the posterior cardinal teeth, which 

 recall its relations to Dosiniopsis of the Eocene. 



Dosinia (Dosinidia) elegans Conrad. 



Artemis elegans Conrad, Proc. Acad. Nat. Sci. Phila., i., p. 325, 1843 ; Am. Journ. Sci., 



2d Ser., ii., p. 393, 1846. 



Artemis concentrica Reeve, Conch. Icon., vi., pi. ii., fig. i, 1850; not of Born, 1780. 

 Dosinia concentrica Tuomey and Holmes, Pleioc. Fos. S. Car., p. 82, pi. xxi., fig. 7, 1855. 

 Dosinia elegans Deshayes, Cat. Conch. Brit. Mus., p. 29, 1853 ; H. and A. Adams, Gen. 



Rec. Moll., ii., p. 431, 1857; Dall, Bull. 37, U. S. Nat. Mus., p. 56, 1889. 

 Artemis transversus Emmons, Geol. Rep. N. Car., p. 295, figs. 223, 224, 1858. 

 Dosinia intermedia Conrad, Proc. Acad. Nat. Sci. Phila. for 1862, p. 575, 1863; Meek, 



Checkl. Mio. Fos., p. 10, 1864. 

 Pectunculus albidus, etc., Lister, pi. cclxxxviii., fig. 124, 1685. 



Upper Miocene of the Chesapeake horizon at Alum Bluff, Florida, and of 

 the Sumter district, South Carolina ; Pliocene of Florida, in the Caloosahatchie 

 beds on the Caloosahatchie River, at Shell Creek and Alligator Creek ; Pleisto- 

 cene of North Creek, near Osprey, Florida ; Dall. Living in the warm water 

 off Cape Hatteras, North Carolina ; Charleston, South Carolina ; west mouth 

 of the St. John's River, East Florida (Britt) ; West Florida, Tortugas, Texas 

 and southward to Yucatan and St. Thomas. 



This fine, flat, and evenly concentrically sculptured species is one of those 

 long confused under the name of concentrica, but it is not the Venus concen- 

 trica of Born. Misled by the confusion, I referred the species collected at 

 Porto Rico to this name, but the specimens really belong to D. concentrica, as 

 subsequent study has shown me. The Pliocene form described by Tuomey 



