ART. 4 NEW UEOCOPTID LAND SHELLS FROM MEXICO BAETSCH 9 



ing numerous closely appressed slender threads which have almost 

 the appearance of lamellae. These threads encircle the entire whorl. 

 Aperture subtriangular, peristome thin, expanded and reflected. The 

 internal axis is moderately large and hollow ; in the last whorl it is 

 rather slender without even a twist. In the penultimate whorl a 

 very strong fold develops on the middle of the pillar which almost 

 disappears in the next whorl posterior to it. In the penultimate 

 whorl also the strong parietal fold develops and reaches its maximum 

 strength, almost disappearing in the whorl posterior to it. The same 

 holds good of the basal fold. The parietal fold also is present in the 

 penultimate whorl but not in the whorl posterior to it. 



The type (Cat. No. 362178 U.S.N.M.) was collected by C. R. Orcutt 

 on a hill east of San Pedro, San Luis Potosi, Mexico. It has 14.2 

 whorls and measures — length, 17.6 mm. ; diameter, 4.1 mm. 



Cat. No. 362179 U.S.N.M. contains 16 paratypes, 10 of which are 

 perfect and yield the following measurements : 



I take pleasure in naming this specimen for Thomas Creighton, to 

 whom I am indebted for many hours of painstaking help in the 

 preparation of material for description. 



HOLOSPIRA (HOLOSPIRA) AMALTHEA, new species 



Plate 1, fig. 13 



Shell elongate-conic, pale brown. Nuclear whorls 2i/^, well 

 rounded, finely granular. Postnuclear whorls increasing slowly in 

 size, appressed at the summit, the early ones moderately rounded, the 

 middle ones almost flattened, and the later ones again moderately 

 rounded. Those following the nuclear turns marked by strong retrac- 

 tively slanting axial riblets which are distantly spaced; while the ribs 

 on the next three turns become enfeebled and finally vanish in mere 

 incremental lines. On the last whorl the ribs again appear, becoming 

 fairly well developed on the later portion of the last turn. Suture 

 well marked. Periphery of the last whorl obtusely angulated. Base 

 short, well rounded, rimate, marked by the continuation of the axial 

 riblets. Last whorl solute with a strong angle behind the posterior 

 angle of the aperture and a lesser one at the junction of the outer 

 and basal lip. The last whorl is marked behind the aperture by 

 numerous closely spaced irregular axial riblets which completely 

 encircle the whorl. Aperture broadly ear shaped, decidedly angu- 

 lated at the posterior angle; outer lip broadly expanded and re- 



