TRANSACTIONS OF WAGNER 

 1534 



'^^^ TERTIARY FAUNA OF FLORIDA 



Family DISCINID.^. 



Genus DISCINISCA Dall. 



Discinisca lugubris Conrad. 



Plate 58, Figure 13. 



Capulns lugubris Conrad, Journ. Acad. Nat. Sci. Phila., vii., p. 143, 1834. 



Orbicula lugubris Conrad, Fos. Medial Tert., p. 75, pi. xliii., fig. 2, 1845 ; Tuomey and 



Holmes, Pleioc. Fos. S. Car., p. 17, pi. v., fig. i, 1855. 

 Discina lugubris Meek, Miocene Checkl., p. 3, 1864; Whitfield, Miocene Moll. N. J., p. 23, 



pi. i., figs. 1-3, 1895. 

 Discinisca lugubris Dall, in Bull. U. S. Geol. Survey No. 87, p. 219, 1897. 

 Orbicula lugubris Emmons, Geol. Rep. N. Car., p. 274, fig. 187, 1858; Conrad, Proc. 



Acad. Nat. Sci. Phila., xiv., p. 582, 1863. 

 Orbicula multilincata Conrad, Fos. Medial Tert., p. 75, pi. xliii., fig. 3, 1845; Tuomey 



and Holmes, Pleioc. Fos. S. Car., p. 18, pi. v., fig. 2, 1855 ; Conrad, Proc. Acad. Nat. 



Sci. Phila., xiv., p. 582, 1863. 

 Discinisca muliilineata Dall, Bull. U. S. Geol. Survey No. 87, p. 219, 1897. 



Older Miocene of Shiloh, Cumberland County, New Jersey, Burns; Mio- 

 cene of Atlantic City, New Jersey, in artesian borings ; of Maryland, in St. 

 Mary's County ; of A^irginia at Petersburg and City Point ; of North Carolina 

 at Magnolia and the Natural Well, Duplin County ; of South Carolina, on the 

 Peedee River ; Pliocene of the Caloosahatchie marls in south Florida. 



This well-known species is characteristic of the true Miocene of the United 

 States eastern coastal plain, only one specimen having been found in the Plio- 

 cene, and that may have been derived from a Miocene source. The radiating 

 threads from which the multilineata takes its name are variable in number and 

 strength and are formed on a thin outer stratum of the shell, which frequently 

 scales off, leaving a concentric sculpture with no traces of radials. I have no 

 doubt that the two nominal species should be consolidated. 



In cleaning out a large Area from the Miocene of Virginia I found a speci- 

 men of this species in situ, and was able, by using great care, to detach the 

 greater part of the lower valve in fairly good condition, confirming the refer- 

 ence of the species to the genus Discinisca. As it is extremely rare to find 

 any trace of the lower valve in the Tertiary marls I have had the remains of 

 this one figured. The valve is as thin as tissue-paper, with, on its upper sur- 

 face, a low but sharp median septum, extending from just in front of the' 

 peduncular foramen to the posterior end of a ilat, lanceolate riblet, which in 

 its turn extends forward in the same line, nearly reaching the front margin. 

 The foramen is clean-cut, narrow, and extends nearly to the middle of the 



