44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I25 



The type, U.S.N.M. No. 561641, comes from the Pliocene of North 

 St. Petersburg-, Fla. It has "j.d whorls and measures : Length 4.4 mm., 

 diameter 1.3 mm. 



PYRGISCUS SOMNUSI, new species 

 Plate 8, figures 4a, b 



Shell rather large, turrited, reddish cream-colored. All but the last 

 7 whorls decollated. Those remaining are flattened and crossed by 

 moderately strong, vertical, axial ribs, of which 14 are present upon 

 the first and second of the remaining whorls, 16 upon the third and 

 fourth, 17 upon the fifth, 22 upon the sixth, while beyond this the 

 ribbing becomes gradually finer and more closely spaced, showing 

 senescent features. The intercostal spaces are about as wide as the 

 ribs ; they are crossed by 6 spiral pits which vary in size and spacing 

 (see detailed sketch, pi. 8, fig. 4b). Suture moderately impressed. 

 Base hemispherical, smooth. Aperture obliquely oval, columella 

 straight, slightly reflected and provided with an oblique fold a little 

 below its insertion ; outer lip thin. 



The type, U.S.N.M. No. 561642, comes from the PHocene of North 

 St. Petersburg, Fla. It has the last seven whorls which measure: 

 Length 5 mm., diameter 1.2 mm. Another decollated specimen is in 

 the collection of the A.N.S.P. 



This species is nearest related to Pyrgiscns sisyphusi (below), from 

 which its much stouter shape, as well as its spiral sculpture, readily 

 distinguishes it. 



PYRGISCUS SISYPHUSI, new species 

 Plate 8, figures 5a, b 



Shell moderately large, turrited, slender, cream-colored. The early 

 whorls in both our specimens are decollated. The remaining post- 

 nuclear whorls are rather high and flattened and are crossed by 

 slightly retractively slanting axial ribs which are of the same strength 

 from the summit to the periphery. Of these ribs 17 are present upon 

 the first to third of the remaining whorls, 20 upon the fifth, and 22 

 upoa the last. The intercostal spaces are about as wide as the ribs and 

 are crossed by six spiral pits which are of unequal size and spacing 

 (see detailed sketch, pi. 8, fig. 5b). Suture rendered wavy by the 

 summit of the axial ribs. Base rather long, hemispherical, marked 

 by the feeble continuation of the axial ribs which extend slightly 

 beyond the periphery and vanish a little distance anterior to this. 

 There is also a deep spiral pit which shows slightly in the suture of 



