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PKOCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 70 



lively slanting, axial riblets. On the middle turns these riblets be- 

 come only a trifle less strong. On all the whorls they are less than 

 half the width of the spaces that separate them. On the last two turns 

 they again increase materially in size. Suture moderately constricted. 

 Periphery angulated. Base short, almost flattened, narrowly perfor- 

 ated, marked by the somewhat enfeebled continuations of the axial 

 ribs. The last portion of the last whorl is solute, and has the axial ribs 

 encircling it as bands. On the extreme last portion, immediately be- 

 hind the peristome, they become enfeebled and closely crowded. Aper- 

 ture moderately large, subtriangular ; parietal wall sinuous ; peristome 

 expanded and reflected. The internal pillar is slender, somewhat 

 twisted, and in the last 31/2 whorls there is a very strong submedian 

 fold which reaches its highest development in the third to last turn. 

 Here, too, the parietal fold reaches its greatest development. This is 

 suspended vertically from the roof of the turn and its basal portion 

 IS bent outward almost at right angles to the main portion. The 

 basal lamella, too, finds its greatest development in this turn, as 

 does the labial fold. 



The type (Cat. No. 363138 U.S.N.M.) was collected by C. R. 

 Orcutt. Unfortunately no specific locality is cited. It has 17.4 

 whorls and measures — length, 13.5 mm.; diameter, 3 mm. Twenty- 

 five paratypes (Cat. No. 363139 U.S.N.M.) are present, 9 of which 

 are complete and yield the following measurements : 



HOLOSPIRA (HOLOSPIRA) CREIGHTONI, new species 



Plate 1, fig. 4 



Shell cylindroid, pinkish white. Nuclear whorls 2.2, strongly 

 rounded, increasing slowly in size, marked by fine granules only, the 

 early postnuclear whorls forming a slender cone; the first 3 well 

 rounded, marked by moderately strong, decidedly retractively slant- 

 ing axial riblets, the rest almost smooth excepting the last 21/2? on 

 the first of which the ribs again become apparent, while on the last 

 they are quite strong. The last whorl is decidedly attenuated anteri- 

 orly. Periphery rounded. Base short, narrow, well rounded, with 

 an umbilical chink. The last portion of the last whorl is solute and 

 bears a strong carina at the posterior angle of the aperture and an 

 obsolete one at the junction of the inner lip and parietal wall. On 

 this portion of the whorl the axial ribs are very much reduced, form- 



