2, PROCEEDINGS OF THE NATIONAL MUSEUM vol. 70 



to increase in size toward the apex and becomes very much con- 

 tracted in the last turn. There is a slight twist a little nearer the 

 base of the whorls than the middle. The pillar also is marked axially 

 by slender retractively slanting threadlike riblets. There are no 

 lamellae. 



The type (Cat. No. 363129, U.S.N.M.) was collected by C. R. Orcutt 

 at Balsas Station, Guerrero, Mexico. It has 19.5 whorls, and meas- 

 ures — length, 21.9 mm. ; diameter, 5.5 mm. 



The type, plus 99 topotypes (Cat. No. 363130 U.S.N.M.), yield the 

 following measurements : 



HOLOSPIRA (COELOSTEMMA) ADRIA, new species 



Plate 1, fig. 1 



Shell small, jDupoid. Nuclear whorls 2.3, strongly rounded, the 

 first 1^ forming a cylindroid apex with a truncated top, the last 

 one increasing materially in size. The nuclear whorls are finely 

 granulose; the last half of the last turn shows an encroachment of 

 the axial rib sculpture of the postnuclear turns upon it, but this is 

 much enfeebled. The first two postnuclear whorls increasing rapidly 

 in size, form with the nuclear turns a broad conic apex; the major 

 portion of the postnuclear whorls form an almost cylindric spire, 

 the greatest diameter being reached on the fifth whorl after which 

 the diameter of the spire becomes slowly contracted. The early 

 postnuclear whorls are marked by coarse, strong, retractively slant- 

 ing axial riblets, while on the middle whorls these riblets become 

 about doubled in number and much finer and less strongly developed. 

 On the last turn they again become more distantly spaced and 

 heavier. Suture strongly impressed. Periphery of the last whorl 

 obscurely angulated. Base short, well rounded, narrowly perforated. 

 The last portion of the last whorl is solute. On this the axial ribs 

 become much enfeebled, closer spaced, irregular and irregularly 

 crowded. They extend all around this portion. Aperture sub- 

 circular; parietal wall flattened; peristome slightly expanded and 

 reflected. In the ground-down specimen the hollow pillar is shown 

 to increase steadily in size from the anterior to the posterior end of 

 the shell, becoming ver}^ much expanded in the apical whorls. In 

 the last whorl it is slender. The pillar is marked by numerous lines 

 of growth and rather feebly developed axial threads. There are 

 no spiral lamellae. 



