NO. 2 PYRAMIDELLID MOLLUSKS — BARTSCH 43 



PYRGISCUS TANTALUSI, new species 

 Plate 7, figures 6a, b 



Shell large, turrited, cream-yellow. The early whorls were lost; 

 those remaining are strongly rounded and marked by axial ribs, which 

 are protractively slanting on the first three of the remaining whorls 

 and vertical upon the rest. Of these ribs 12 are present upon the first, 

 14 upon the second and third, 15 upon the fourth, 16 upon the fifth, 

 18 upon the sixth, 20 upon the seventh, and 21 upon the last whorl. 

 These ribs are of the same strength from the summit to the periphery. 

 The intercostal spaces are strongly impressed and about as wide as 

 the ribs. They are marked by six broad spiral pits, of which the first 

 five are subequal while the basal one is much wider (see detailed 

 sketch, pi. 7, fig. 6b). Suture well marked, rendered wavy by the 

 summits of the ribs. Base short, hemispherical, smooth. Aperture 

 subquadrate, columella slender, provided with an oblique fold a 

 little below its insertion ; outer lip thin. 



The type, U.S.N.M, No. 561640, comes from the Pliocene of North 

 St. Petersburg, Fla. It is a fragment consisting of the last 8 whorls 

 and measures: Length 5 mm., diameter 1.5 mm. 



The large size, almost cylindric outline, and strongly rounded whorl 

 distinguish this species from Pyrgiscus sylvanusi (below). 



PYRGISCUS SYLVANUSI, new species 

 Plate 7, figures 3a, b 



Shell small, turrited, cream-yellow. The nucleus consists of 2.5 

 strongly rounded whorls, which form a depressed helicoid spire whose 

 axis is at right angles to that of the postnuclear whorls, in the first 

 of which it is about one-fourth immersed. The postnuclear whorls 

 are moderately rounded and crossed by moderately strong vertical 

 ribs, of which 10 are present upon the second, 14 upon the third, 18 

 upon the fourth, 20 upon the fifth, 21 upon the sixth, and 23 upon the 

 last turn. These ribs are of equal strength from the summit to the 

 periphery. The intercostal spaces are about as wide as the ribs and 

 are crossed by six spiral pits, of which the last four are of equal 

 strength, the first being about half as wide as these and the second 

 half as wide as the first. The spacing of these pits is irregular and 

 best noted by examining the detailed sketch, plate 7, figure 3b. Suture 

 well impressed. Base hemispherical, smooth. Aperture obliquely 

 oval, columella slightly twisted, moderately stout and reflected, pro- 

 vided with a weak fold a little below its insertion, outer lip thin, 

 parietal wall glazed with a weak callus. 



