NO. 2 PYRAMIDELLID MOLLUSKS — BARTSCH 39 



ceeding turns, in the first of which it is about one-third immersed. 

 Postnuclear whorls rather high, moderately rounded, separated by 

 a well-impressed suture. They are crossed by axial ribs, which are 

 stronger and more distantly spaced and vertical on the first three 

 whorls, beyond which they become finer and more closely spaced and 

 slightly retractively slanting. These ribs extend equally strong from 

 the summit to the periphery. Of these ribs 12 are present upon the 

 second whorl, 14 upon the third, 16 upon the fourth, 22 upon the 

 fifth, 26 upon the sixth, 28 upon the seventh, and 34 upon the last 

 whorl. The axial ribs render the whorls slightly crenulated at the 

 summit. The intercostal spaces vary in width like the ribs and are 

 about as wide as the ribs. They are marked by five strong spiral pits, 

 of which the upper three are of equal spacing, the first being about as 

 far below the summit as the third is separated from the fourth that 

 is about double the space as that separating the first three pits; the 

 last two pits are slightly more distantly spaced than the first three. 

 The base is subhemispherical with a few irregularly spaced, faint 

 spiral lines. Aperture subquadrate columella reflected, bearing a weak 

 fold near its insertion, outer lip thin, parietal wall covered with a 

 thin callus. 



The type, U.S.N.M. No. 561630, comes from the Pliocene deposits 

 of North St. Petersburg, Fla. It has 8.5 postnuclear whorls and 

 measures: Length 4.4 mm., diameter i.i mm. 



The closely spaced axial ribs of the later postnuclear whorls readily 

 distinguish this species from the other, having five incised spiral pits 

 in the intercostal spaces. 



PYRGISCUS VISHNUI, new species 

 Plate 7, figures 2a, b 



Shell small, turrited, rather stout, cream-yellow. Nucleus small, 

 more than half immersed in the first postnuclear turn. The postnu- 

 clear whorls are strongly rounded, marked by strong, slightly retrac- 

 tively slanting axial ribs, of which 12 are present upon the second, 

 14 upon the third, 16 upon the fourth and fifth, 17 upon the sixth, 

 20 upon the seventh, and 21 upon the last whorl. These ribs are 

 about as wide as the spaces that separate them, and they extend 

 equally strong from the summit to the periphery. Their summits 

 render the suture wavy. The intercostal spaces are strongly impressed 

 and marked by five deep spiral pits. Base hemispherical, smooth. 

 Aperture subquadrate, columella stout, reflected, bearing a feeble 

 oblique fold near its insertion, outer lip fractured, parietal wall covered 

 by a thin callus. 



