NO. 2 PYRAMIDELLID MOLLUSKS — BARTSCH 45 



the preceding turns but extends below the periphery as a spiral band. 

 This makes our sketch (pi. 8, fig. 5b) appear as if seven spiral bands 

 were present. The rest of the base is smooth. Aperture elongate- 

 oval, columella slender, curved, and provided with an oblique fold a 

 little below its insertion, outer lip thin, parietal wall covered by a 

 thin callus. 



The type, U.S.N.M. No. 561643, comes from the Pliocene of North 

 St. Petersburg, Fla. It has 6.5 whorls remaining which measure: 

 Length 4.5 mm., diameter i.i mm_. Another specimen of about the 

 same size is in the collection of the A.N.S.P. 



This species resembles most nearly Pyrgiscus somnusi (p. 44), 

 from which it is easily distinguished by its much more slender form 

 and spiral sculpture. 



PYRGISCTJS SILENUSI, new species 

 Plate 8, figures 3a, 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 whorls, in the first of which the nuclear turns are about 

 one-fourth immersed. The postnuclear whorls are flattened and 

 marked by rather weak, retractively slanting axial ribs which are 

 merely indicated upon the first two whorls; the third whorl shows 15, 

 the fourth 18, the fifth and sixth 20, and the last 22. The intercostal 

 spaces are about as wide as the ribs and are crossed by six spiral pits, 

 of which the first five are subequal and subequally spaced. The first 

 pit is about three times the distance below the summit as it is from 

 its neighbor. The sixth pit is double the width of the rest. (See 

 detailed sketch, pi. 8, fig. 3b.) Suture not strongly impressed. Base 

 hemispherical, smooth. Aperture obliquely oval, columella provided 

 with an oblique fold a little anterior to its insertion, outer lip frac- 

 tured, parietal wall glazed by a weak callus. 



The type, U.S.N.M, No. 561644, comes from the Pliocene of North 

 St. Petersburg, Fla. It has 7 postnuclear whorls and measures: 

 Length 3.5 mm., diameter i mm. 



It is nearest related to Pyrgiscus pyrrhusi (below) but is dis- 

 tinguished from that by its different spiral sculpture and less strongly 

 developed axial ribs. 



PYRGISCUS PYRRHUSI, new species 

 Plate 8, figures la, b 



Shell small, turrited, cream-yellow. Nuclear whorls 2.3, strongly 

 rounded, forming a rather elevated, helicoid spire whose axis is at 



