142 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. ."^.XXI. 



The following table gives measurements of the 8 specimens: 



Measurements of Ilolospira {Liostemma) hamiltoni. 



'< Type. 



HOLOSPIRA (LIOSTEMMA) DURANGOENSIS, new species. 



Plate III, lig. 8. 



Shell very large, solid, cylindric-conic, white. Nuclear whorls 2,' 

 large, inflated, minutel}- granulose. Succeeding whorls moderately 

 rounded. Terminal cone gently tapering. The whorls are crossed 

 by numerous very oblique, obsolete threads, which are a little more 

 distinct on the early whorls than the rest, and ))ecome practically 

 altogether lost on the cylindrical part of the spire. The penultimate 

 whorl becomes decidedly narrowed basall}", and is crossed b}' a series 

 of quite distinct riblets, which are more strongly developed below the 

 slightly angulated periphery and on the rounded base than near 

 the summit. Basedeepl}^ rimate. Last whorl decidedl}" disjunct; the 

 union of the parietal and outer wall is marked by a slender carina, which 

 extends from behind the peristome to the point of dissolution. The 

 entire free portion is marked b}' more or less regular, circular threads, 

 which become weak and closely crowded behind the peristome. Aper- 

 ture roughh' circular, with a very hroadly t'.rpanded., but not reflected, 

 peristome. Internal pillar slender, of uniform width in the cydin- 

 drical part, somewhat wider in the terminal cone, hollow, smooth, 

 without twist or fold, except in the penultimate turn, where a low 

 cord encircles it a little above the floor. 



This is the largest of the known Ilolospii'a. 



