ART. 4 NEW UKOCOPTID LAND SHELLS FEOM MEXICO BAETSCH 13 



come decidedly enfeebled on the next three turns, disappearing 

 shortly thereafter. The middle whorls are smooth, excepting coarse 

 incremental lines. On the last turn the riblets again become appar- 

 ent and on the last portion of the last turn are very strong. Suture 

 slighly impressed. Periphery of the last whorl broadly obtusely an- 

 gulated. On the last whorl there is a constriction a little posterior to 

 the periphery which becomes decidedly apparent as the whorls pro- 

 gress, so that the outer portion of the last whorl behind the aperture 

 is decidely concave. The last whorl is solute at its extremity, bear- 

 ing a conspicuous broad keel behind the posterior angle of the aper- 

 ture. The solute portion is marked by numerous closely spaced rib- 

 lets wdiich appear like obsolete lamellae. Aperture subquadrate, the 

 outer lip and parietal wall somewhat sinuous, peristome broadly ex- 

 panded and reflected. The internal axis is moderately thick, hollow, 

 decidedly contracted in the last whorl and a little less so in the penul- 

 timate. In the latter turn the columellar fold begins as a slender 

 cord and reaches its greatest development in the whorl preceding 

 this. Here, too, the outturned strong parietal lamella appears and 

 disappears. The same holds true of the basal fold and the 'slender 

 labial cord. 



The type (Cat. No. 363143 U.S.N.M.) was collected by C. R. 

 Orcutt at Topochico Mountain, Monterey, Nueva Leon, Mexico. It 

 has 15.4 whorls and measures — length, 17.8 mm.; diameter, 4,5 mm. 

 Cat. No. 363144 U.S.N.M. contains five fragments of paratypes. 



EXPLANATION OF PLATES 



Fig. 1. Holospira (Coclostemma) adria. 



2. Holospira (Bostrichocentrum) curybia. 



3. Holospira {Holospira) pedroana. 



4. Holospira (Holospira) creightoni. 



5. Holospira (Holospira) topochicoana. 



6. Holospira (Bostrichocentrum) galathea. 



7. Holospira (Holospira) alvarezensis. 

 S. Holospira (Holospira) andromeda. 

 9. Holospira (Holospira) mitraensis. 



10. Holospira (Holospira) bachia. 



11. Holospira (Ti'istemma) melea. 



12. Holospira (Coelostemma) iqualaensis. 



13. Holospira (Holospira) amalthea. 



14. Holospira (Coelostemma) aduna. 



15. Holospira (Tristemma) hyper ia. 



16. Holospira (Coclostemma) halsasensia. 



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