INSTITUTE OF SCIENCE, PHILADELPHIA. 7 



callus is distinct in the adult ; posterior inner edge of the outer lip with an 

 excavation in front of which is a projecting thicker part which in the oldest 

 specimens is almost toothlike; the reflected face of the lips lies in one plane; 

 the aperture slightly compressed laterally. Lon. of shell ii.o; of aperture 4.5; 

 lat. of shell 4.0 mm. 



Silex-beds of Ballast Point, Tampa Bay; collected by Dall and Burns. 



This species has a differently formed and relatively shorter mouth and 

 much heavier lip than the others. Like them it varies somewhat in size and 

 proportions. Figure 6b is intended to show the callus and the groove at the 

 junction of the body and outer lip. Sometimes, however, the callus is of a leaf- 

 shape, with the groove in the center, like the midrib of a laurel leaf In B. 

 americanus this is especially prominent. The groove in the figure is a little 

 too straight, as it has usually a slight flexure to correspond with the convex 

 surface upon which it lies. 



Bulinaulus (? Anctus) americanus Dall. 

 Plate I, figures 9, 9 a. 

 Partula americana Heilprin, Trans. Wagner Inst. I. p. 115, pi. xvi. fig. 60, 1887. 

 Silex-beds of Ballast Point and vicinity, abundant ; a single, possibly 

 adventitious specimen in the Orbitolite bed at the same locality in the upper- 

 most stratum. Collected by Messrs. Shepard, Willcox, Newman, Heilprin, 

 Dall and Burns. 



This species, though showing some slight variations, is on the whole 

 remarkably constant in form and size, averaging in length of shell 17, of aper- 

 ture 8, and maximum diameter 8 mm. The reflected lip, though wide, is not 

 heavy, but the callus uniting the lips over the body and the groove at the 

 commissure are relatively more conspicuous than in the smaller species. No 

 trace of spiral scratching or sculpture has been discovered after examining many 

 specimens. The varieties were found with the typical form, but seem tolerably 

 constant. 



Bulimulus (? Anctus) Stearnsii Dall. 



Plate I, figure 12. 



Shell small, elongated, with five or more whorls; surface nearly smooth or 

 slightly transversely striated in harmony with the incremental lines and with 

 faint indications of microscopic spiral striae ; type-specimen decollate ; whorls 

 slightly rounded, appressed at the distinct but not channelled suture ; last 

 whorl rather long, with a very narrow chink behind the reflected inner lip ; 



