TERTIARY MOLLUSKS OF FLORIDA. 

 PART I. 



GASTROPODA, 



CONTINUED AND CONCLUDED ; TOGETHER WITH ADDITIONS TO THAT PART OF 

 THE FAUNA DISCUSSED IN PART I. 



Order OPISTHOBRANCHIATA. 



Family BULLIDtE (supplementary). 



Bulla striata Brug. var. attenuata Dall. 



Plate 13, figure 10 a. 



Habitat, Pliocene of Shell Creek, Willcox. 



Among the specimens of this common species obtained at Shell Creek 

 were a number which at first seemed as if they must certainly belong to a 

 different species. I have come to the conclusion that they are merely a 

 variety of the ordinary form ; but they present such marked characters 

 that it has seemed well to illustrate them. This variety differs from the com- 

 mon form of striata by being distinctly attenuated behind, by the presence at 

 the posterior extreme of four or five sharp spiral grooves even more promi- 

 nent than those near the pillar, and by the much larger size of the apical pit.whose 

 walls are distinctly spirally grooved. Intermediate specimens, however, do 

 occur, and therefore this form can only take rank as a variety. I have not 

 found in a large series of recent specimens any exactly comparable to it. 



Family TORNATINID^ (supplementary). 



TJtriculus vaginatus Dall. 



Plate 20, figure 2. 



This species, described in Part I. (p. 16), is figured from a young specimen 



obtained from Ballast Point. The adult is proportionately broader and 



squarer in form, but otherwise does not materially differ. 



Order CTENOBRANCHIATA. 



Family CONID^ (supplementary). 

 Oonus planiceps Heilprin. 

 Part i. p. 25, pi. II, figures 5, 5 a. 

 This species has since turned up at Bailey's Mill creek sink, in Jefferson 

 County, Florida, about three miles southwest of Lloyd's Station, on the rail- 

 way. Here it is associated with a number of other characteristic fossils of the 

 Orthaulax bed. The fossils occur here in a sort of clay overlying a bed of 

 limestone, and are in the form of siliceous pseudomorphs, as at Ballast Point. 



