48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



tractively slanting axial ribs, of which in the cotype having the nuclear 

 spire 12 are present upon the second and third whorl, 14 upon the 

 fourth and the rest. The adult cotype has the last 6.3 whorls remain- 

 ing, of which the first has 14 ribs, the second 16, and the rest 18. 

 These ribs extend equally strong from the summit to the periphery. 

 The intercostal spaces are about as wide as the axial ribs; they are 

 crossed by seven spiral pits, of which the first is a mere line, while 

 the second, third, and fourth are very large, being only excelled in 

 width by the last, the fifth and sixth being a little narrower than the 

 three above it. (The sketch, pi. 9, fig. ib, gives details of size and 

 spacing.) Suture moderately well impressed, rendered wavy by the 

 summit of the axial ribs. Base hemispherical, smooth. Aperture 

 broad, obliquely oval, columella vertical, rather slender, and slightly 

 reflected, bearing an oblique fold a little below its insertion, outer 

 lip fractured, parietal wall glazed with a thin callus. 



The two CO types, U.S.N.M. No. 561649, come from the Pliocene 

 of North St. Petersburg, Fla. The specimen with the nucleus has 

 8.4 postnuclear whorls and measures: Length 4.2 mm., diameter 

 1.3 mm. The other cotype has the last 6.5 postnuclear whorls and 

 measures: Length 4.8 mm., diameter 1.5 mm. U.S.N.M. No. 561650 

 contains two specimens from the same source. Two additional speci- 

 mens are in the collection of the A.N.S.P. 



This species differs from Pyrgiscus dianae (p. 47) in not being 

 broadly conic and in details of the spiral sculpture. 



PYRGISCUS PHAETONI, new species 



Plate 8, figures 6a, b 



Shell moderately large, turrited, not stout, elongate, cream-colored. 

 The nucleus has 2.3 strongly rounded whorls, which form a moder- 

 ately elevated helicoid spire whose axis is at right angles to that of 

 the axis of the postnuclear whorls, in the first of which it is about 

 one-fourth immersed. The postnuclear whorls are flattened and 

 crossed by decidedly retractive axial ribs, of which in the type, which 

 has lost the nucleus and the first two postnuclear whorls, 18 are 

 present on the second to fifth of the remaining turns, 20 on the sixth, 

 and 22 on the last. The intercostal spaces are narrower than the ribs 

 and bear seven spiral pits which vary greatly in width and spacing 

 and are best described by our detailed sketch (see pi. 8, fig. 6b). 

 Suture moderately constricted, rendered wavy by the summits of the 

 axial ribs. Base hemispherical, smooth, excepting a fine incised spiral 

 line which is at a little distance below the periphery. The axial ribs 

 extend feebly beyond the periphery to this line. Aperture obliquely 



