NO. 2 PYRAMIDELLID MOLLUSKS — BARTSCH 73 



The type, U.S.N.M. No. 561714, comes from the Pliocene of North 

 St. Petersburg, Fla. It has 6.8 postnuclear whorls and measures: 

 Length 3.9 mm., diameter 1.5 mm. 



The umbilicated base will readily distinguish this species from 

 Chrysallida locklini (below). 



I take pleasure in naming this species for Isaac Lea, who donated 

 his immense unique collection of mollusks to the United States Na- 

 tional Museum. He published many volumes on American Unionidae 

 and other mollusks. He is also the author of numerous descriptions 

 of southeastern United States Tertiary fossils. 



CHRYSALLIDA LOCIO^INI, new species 

 Plate 16, figure 10 



Shell moderately large, elongate-conic, cream-yellow. The nucleus 

 consists of almost 2 well-rounded turns, which form a low helicoid 

 spire whose axis is at right angles to that of the postnuclear whorls, 

 in the first of which it is about one-third obliquely immersed. The 

 postnuclear whorls are slightly rounded, shouldered at the summit, 

 and marked by strong, retractively slanting axial ribs, which are of 

 equal strength from the summit to the periphery. Of these ribs 12 

 are present upon the second, 14 upon the third, 16 upon the fourth, 

 18 upon the fifth, and 19 upon the last whorl. The sculpture on the 

 first whorl is obsolete. The intercostal spaces are about as wide as 

 the ribs. The spiral sculpture consists of four equally strong cords 

 that equal the ribs in strength. The spiral cords are separated by 

 equally wide spaces. The junctions of the axial ribs and spiral cords 

 form almost round, strongly elevated tubercles while the spaces be- 

 tween them are deep, round pits. The suture is deeply channeled and 

 rendered wavy by the tubercles at the summit of the whorls. The 

 periphery is marked by a spiral cord which is about half as wide as 

 those on the spire and separated from them by a channel a little wider 

 than that separating them. The peripheral cord shows feeble nodules. 

 The base is rather long, strongly rounded, and marked by seven 

 spiral cords, which grow consecutively smaller from the periphery 

 basalward. In addition to this the base shows numerous slender axial 

 threads. The aperture is oval, somewhat effuse at the junction of the 

 basal lip and columella ; the columella is thin-edged, slightly sinuous, 

 and bears a strong fold at its insertion ; the parietal wall is glazed by 

 a thin callus ; the outer lip is gently curved and rendered wavy by the 

 external spiral cords. 



The type, U.S.N.M. No. 561 7 15, comes from the Pliocene of North 



