FREE INSTITUTE OF SCIENCE 

 TERTIARY FAUNA OF FLORIDA 



within the limits of varietal rather than specific distinction. The specimen 

 figured is somewhat blunted by fracture or other accidental causes at the 

 lower posterior end, so that it does not show as much of the produced char- 

 acter as the other smaller and less developed specimens which were collected 

 with it. 



Modiolaria lateralis Say. 

 Mytillus lateralis Say, Journ. Acad. Nat. Sci. Phila., ii., p. 264, 1822 ; Binney's Say, p. 



91, 1858. 

 Crenella lateralis Tryon, Am. Mar. Conch., p. 190, pi. 40, fig. 523, 1874. 

 Modiolaria lateralis Dall, Bull. U. S. Nat. Mus., No. 37, p. 40, pi. 6, figs. 7, 8, 1889. 

 Modiola elliptica H. C. Lea, Am. Journ. Sci., xliii., p. 106, pi. i, fig. 2, 1842. 



Pliocene of the Caloosahatchie and Shell Creek marls, Florida, Dall and 

 Willcox ; Pleistocene of Simmons Bluff, South Carolina, Burns ; recent at 

 Portland, Maine (Fuller) ; Delaware Bay, Lea ; North Carolina, United States 

 Fish Commission ; South Carolina, Gibbes ; and southward through the 

 Antilles to Venezuela; situs on oysters and sponges {TetJiyd). 



This pretty little species is much like M. niarmorata Forbes of the British 

 fauna. It is probable that specimens obtained north of Chesapeake Bay have 

 been transported with " seed" oysters. Modiolaria translucida Gabb (Journ. 

 Acad. Nat. Sci. Phila., 2d Sen, viii., p. 377, pi. 47, fig. 81, 1881) from the Plio- 

 cene of Costa Rica is a very similar species. 



The recent northern species, M. nigra Gray and M. discors L., are reported 

 by Dawson (Can. Nat, 2, p. 419, and Geol. Rep. Can. for 1863, p. 927) 

 from the Pleistocene glacial beds of the Province of Quebec, near Montreal. 



Family DREISSENSIID^. 



The systematic position of this family cannot yet be said to be definitely 

 fixed, and is not likely to be finally decided until careful anatomical and 

 embryological investigations of such forms as Scptifer, Mytilopsis, etc., are 

 available. 



The nomenclature of this group has, so far as I know, never been pub- 

 lished in the full and precise shape demanded by systematists of the present 

 day ; those who have referred to it seem to vie with each other in omitting 

 dates, references, and essential facts. To make such a review here is not 

 called for by present necessities, and is impracticable for want of part of the 

 literature. The earliest name appears to be EnoceplLalns (Miinster MS., 1828) 

 Keferstein (Geogn. Geol. Zeitschr., ix., p. 92, 1831), but it would seem as if the 



