38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



Incised spiral lines not 6. 

 Incised spiral lines 7. 

 Shell stout. 



Whorls strongly rounded apolloi 



Whorls not strongly rounded. 



Shell broadly conic dianae 



Shell not broadly conic latonae 



Shell not stout. 



Shell very elongate phaetoni 



Shell not very elongate. 



Axial ribs retractive harmoniae 



Axial ribs vertical cadmusi 



Incised spiral lines 8. 

 Shell large. 



Whorls shouldered inoae 



Whorls not shouldered telamoni 



Shell not large. 



Shell slender hehcae 



Shell not slender aesoni 



PYRGISCUS YAMAI, new species 

 Plate 6, figures 6a, b 



Shell small, turrited, cream-colored. Nuclear whorls 2.5, forming 

 a depressed helicoid spire whose axis is at right angles to that of the 

 succeeding turns, in the first of which it is almost half immersed. 

 Postnuclear whorls moderately round, marked by strong, vertical 

 axial ribs which render the suture wavy at the summit. Of these 

 ribs 14 are present upon the third and fourth, 15 upon the fifth, 16 

 upon the sixth, 18 upon the seventh, and 20 upon the last turn. These 

 ribs extend very feebly over the well-rounded hemispherical base. 

 The deeply impressed intercostal spaces are about as wide as the ribs 

 and are crossed by four broad, strongly impressed spiral grooves 

 that are of equal strength but not equal spacing (see detailed sketch). 

 Aperture subquadrate, columella slender, outer lip thin, parietal wall 

 covered by thin callus. 



The type, U.S.N.M. No. 561629, has 8.5 postnuclear whorls and 

 measures: Length 4.5 mm., diameter i mm. It comes from the 

 Pliocene deposits of North St. Petersburg, Fla. Another specimen 

 from the same source is in the collection of the A.N.S.P. 



PYRGISCUS ZETHUSI, new species 



Plate 7, figures 7a, b 



Shell small, turrited, cream-yellow. Nuclear whorls 2.5, forming 

 a low helicoid spire whose axis is at right angles to that of the sue- 



