4 TRANSACTIONS OF THE WAGNER FREE 



Helicina ballista var. tampse Dall. 



Shell similar, but smaller, though with the same number of whorls, and an 

 appearance of being slightly flatter on the spire, and generally smooth ; alt. 

 5.0; max. diam. 8.0; min. diam. 6.5 mm. 



Ballast Point silex-beds, upper part, and also in the overlying Orbitolite 

 rock, and in the latter at Six-Mile Run, near Orient Station, east from Tampa 

 City. This species has been compared to H. substriata Gray, now living at 

 Barbados. There are many points of resemblance, but the typical form of the 

 fossil is larger and much heavier, with a stronger lip, which narrows and be- 

 comes thinner near the pillar just where the living species has its thickest and 

 strongest part. In this character the two are the exact opposite of each other. 

 The variety agrees with the typical form of H. ballista as regards this charac- 

 ter. Though the shell is common and has a wider geologic range than the 

 others of this assemblage, no trace of the operculum has been found so far. 

 The specimen figured does not show the spiral lines, which are inconstant in 

 both the fossil and the recent species referred to. 



Family LIMN^ID.E. 



Genus PLANORBIS Guettard. 



Planorbis 'Willcoxii n. s. 



Plate I, figures 6 c, 6 d. 



Shell small, with five or more slowly enlarging rounded whorls ; surface 



sculptured only with inconspicuous incremental lines ; coil dextral (?), upper and 



under surfaces very similar ; upper side more deeply indented with about three 



turns visible, the suture not very deep and the surface slightly flattened ; under 



side with a deeper suture, and the whorls more boldly rounded ; aperture 



lunate, outer lip defective in the specimen, but probably simple and sharp. 



■Diameter of type specimen 6.5 ; altitude 2.3 mm. 



A single specimen was collected at Ballast Point by the writer. 

 This species is most like the recent West Indian P. circiLmlineatus Shuttle- 

 worth, but has more symmetrically rounded whorls, a proportionally smaller 

 altitude, and shows no traces of the spiral lines. The last whorl is much 

 larger in proportion to the rest of the shell in the living form. The fossil is 

 much like several of the species of Segrnentina, S. liavanensis Pfr. and allied 

 recent forms, but it has no internal teeth. 



Family HELICID^. 



Subfamily BULIMULIN^. 



Genus BULIMULUS Leach. 



Section Ancins Albers. 



The Bulitnuli of the Florida Miocene are obviously nearly related to one 



another; and, whatever group they may be referred to, all will be included in 



it. They are characterized by small size, a form somewhat recalling that of 



