NO. 2 PYRAMIDELLID MOLLUSKS — BARTSCH 4I 



very closely spaced. The intercostal spaces are about as wide as the 

 ribs and are crossed by five broad and deep subequally spaced series 

 of spiral pits. Suture moderately well impressed, rendered wavy by 

 the summits of the axial ribs. Base hemispherical, marked by the 

 feeble continuations of the axial ribs and weak indications of fine 

 spiral threads. Aperture obliquely oval, columella thin, somewhat 

 twisted, with an oblique fold near its insertion, parietal wall covered 

 with a thin callus. 



The type, U.S.N.M. No. 561635, comes from the Pliocene of North 

 St. Petersburg, Fla. It has 9 postnuclear whorls and measures: 

 Length 4.5 mm., diameter i.i mm. U.S.N.M, No. 561636 contains 

 II additional specimens from the same source, and 13 more are in 

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



This species is nearest related to Pyrgiscus venusae (p. 40), from 

 which it is readily distinguished by having the axial ribs much less 

 strongly developed and more closely spaced and extending feebly upon 

 the base, which also shows spiral lirations. 



PYRGISCUS THESTIUSI, new species 

 Plate 7, figures 8a, b 



Shell small, broadly conic, cream-yellow. Nucleus lost. The post- 

 nuclear whorls are slightly rounded and crossed by very strong, dis- 

 tantly spaced axial ribs, of which 14 a.re present on all the whorls. 

 The ribs are of equal strength from the summit to the periphery. 

 The intercostal spaces are strongly impressed and about as wide as 

 the ribs ; they are crossed by six spiral pits that vary in strength and 

 spacing (see detailed sketch, pi. 7, fig. 8b). Suture moderately im- 

 pressed, rendered wavy by the summit of the axial ribs. Base hemi- 

 spherical, smooth. Aperture fractured, apparently subquadrate, colu- 

 mella rather thick with an oblique fold near its insertion, outer lip 

 fractured, parietal wall covered by a thin callus. 



The type, U.S.N.M. No. 561637, comes from the Pliocene of North 

 St. Petersburg, Fla. It has 7 postnuclear whorls remaining which 

 measure: Length 4.1 mm., diameter i mm. The broadly conic shape 

 and very strong distantly spaced axial ribs readily distinguish this 

 species from the other members having six spiral pits. 



PYRGISCUS TELLUSAE, new species 

 Plate 7, figures 5a, b 



Shell small, turrited, slender, cream-colored. The nucleus consists 

 of about 2.5 whorls that form a depressed helicoid spire, whose axis 



