90 



HOLOSPIRA. 



3. Whorls Hi/2 ; length 22i/ 2 , diam. 6y 2 mm. 



H. pasonis, no. 14. 



H. cretacea Pfr. (sp. no. 27), may belong near the last 

 three species. 



(Group of H. pasonis.) 

 14. H. PASONIS Ball. PI. 16, figs. 14, 15 ; pi. 23, fig. 74. 



Shell white, mostly smooth but hardly glossy, of eleven and 

 a half whorls; two and a half smooth, inflated, nepionic 

 whorls, the apex flattish, followed by several whorls which are 

 minutely ribbed in harmony with the incremental lines, the 

 ribbing gradually becoming obsolete over most of the shell, 

 but reappearing on the last whorl, especially the basal part, 

 sharper and somewhat crowded just behind the reflected lip ; 

 umbilicus closed or reduced to a minute chink; suture dis- 

 tinct, sutural edge continuing as a keel to the reflected mar- 

 gin of the aperture; aperture very short necked, almost cir- 

 cular, broadly reflected; the pillar, as usual in the genus, 

 tubular above the last whorl, the axis externally simple but 

 somewhat flexuous. Length 22.5, max. diam. 6.5 mm. (Dall). 



Texas: Mule canon, El Paso county, at an elevation of 

 4,000 feet. 



Holospira pasonis DALL, The Nautilus, viii, p. 112 (Feb., 

 1895) ; Ilolospira (Metastoma) pasonis DALL, Proc. U. S. 

 Nat. Mus., xix, p. 348, pi. 31, f. 4, 5. 



"This species is nearest to H. coahuilensis W. G. Binney, 

 which has one or two more whorls, the last two proportion- 

 ately more attenuated with more extended, sharper and more 

 distant sculpture, and obtusely keeled or compressed base 

 resulting in a much more triangular and narrower aperture. 

 It is riot particularly close to any of the other species hitherto 

 described, the H. semistriata [error for semisculpta] Stearns 

 being quite distinct. A marked character is the evenly 

 rounded basal part of the whorl just behind the lip." (Dall). 



The latter half of the last whorl has more numerous and 

 closer riblets in the specimens before me (part of the type 

 lot) than shown in fig. 15, a copy of Dall's figure of the type. 

 The internal pillar is small, about 1 mm. in diam. above, 



