26 



BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



The groove in the figure is a little too straight, as it usually has 

 a slight flexure corresponding to the convex surface upon which 

 the callus lies. 



BULIMULUS (HYPERAULAX) AMERICANUS (Heilprin), 



Plate 2, fig. 5 ; plate 3, fig. 3 ; plate 4, figs. 12, 14. 



Partula americana Heilprin, Trans. Wagner Inst., vol. 1, p. 115, pi. 16, 



fig. 60, 1887. 

 BuUmulus (? Anctus) americanus Dall, Trans. Wagner Inst., vol. 3, pt. 1, 



p. 7, pi. 1, figs. 9, 9a, Aug., 1890 (with varieties partulinus and laxus 



Dall). 



Tampa silex beds at Ballast Point ; one specimen possibly adventi- 

 tious in the overlying Orbitolite bed at the same locality. Collected 

 by Messrs. Shepard, Willcox, Newman, Heilprin, Post^ Dall, and 

 Burns. U. S. Nat. Mus. No. 165009. 



The relations of the typical form and the varieties are shown by 

 the following measurements : <$> 



Number 

 of whorls. 



Height. 



Diameter. 



Aperture. 



Forma typica (fig. 5) 



yariety partulinus (fig. 12) 

 Variety laxus (fig. 14) 



6.5 

 6.0 

 6.0 



mm 

 17.0 

 13.5 

 15.5 



mm 

 9.0 

 7.5 

 7.2 



8.5 

 7.0 

 7.5 



BULIMULUS (HYPERAULAX) TAMPAE, new species. 



Plate 1, fig. 3. 



Shell subf usif orm, of moderate size, with about six whorls ; nucleus 

 smooth, of a whorl and a half; subsequent whorls moderately con- 

 vex, with a distinct, very slightly appressed suture; axial sculpture 

 of fine, equal, regular, equally spaced, somewhat retractive threads 

 or ridges, separated by about equal interspaces, covering the whole 

 surface; base somewhat attenuated; umbilicus minutely perforate, 

 overshadowed by the reflection of the pillar lip ; aperture somewhat 

 elongate, outer lip narrow behind and there hardly reflected, thicker 

 at the beginning of the middle third, and thenceforward more broadly 

 reflected, continuous in front and on the pillar and with a rather 

 thick parietal callus; between the callus and the outer lip at the 

 suture is a very narrow but deep channel. Height 13.7, maximum 

 diameter 6 mm. 



Tampa silex beds. Ballast Point, Tampa Bay, Florida. 



Type from the Post collection, IT. S. Nat. Mus. No. 1G5012. 



BULIMULUS (HYPERAULAX) BALLISTAE, new species. 



Plate 1, fig. 5. 



Shell small, solid, moderately stout, comprising six whorls sepa- 

 rated by a slightly appressed suture; nucleus blunt and rounded; 



