40 



GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



projecting very little forward of the junction 

 of the angular. G. dalliana, no. 13. 



c 1 . Columellar lamella having a small callous 

 below its inner end; parietal lamella project- 

 ing distinctly forward of the junction of the 

 angular. G. d. media, no. 13a. 



& 1 . Coluniellar lamella horizontal in front, the inner 

 end bent down at a right angle. 



c. Peristome continuous; lower palatal and basal 

 folds deeply placed ; Arizona. 



G. bttamellata, no. 14. 



c 1 . Peristome interrupted above; lower palatal 

 and basal folds not deeply placed; columellar 

 lamella larger in a front view; Brazil. 



G. iheringi, no. 35. 



a 3 . Species not included in the key: G. dicrodonta, no. 34; 

 G. pazi, no. 36. 



8. GASTROCOPTA PERVERSA (Sterki). PL 6, figs. 9, 10, 11. 



"Shell sinistrorse, oblong-cylindroconical, horn-colored, 

 translucent ; apex rather acute ; base umbilicate-rimate, the 

 umbilicus partly overlaid by a projecting part of the last 



whorl; whorls 5%, rather slowly and 

 regularly increasing, convex, with the 

 suture moderately deep, the last equal- 

 ing two-fifths of altitude, slightly nar- 

 rowed at the periphery, at last somewhat 

 ascending and then protracted horizon- 

 tally beyond the periphery of the spire, 

 for a length equal to one-third of the 

 diameter, with a rather high, oblique 

 crest-swelling all around, in front of 

 that contracted, and margins broadly 

 everted all around at the aperture; on 

 the palatal side of the protracted part, 

 behind the aperture, a deep longitudinal 

 (== spiral) impression; surface slightly 

 shining, with fine, almost regular, crowded stride; nucleus 



FIG. 12. G. perversa, 

 basal view, most of 

 the last whorl re- 

 moved to show the 

 angular, parietal and 

 columellar lamellae. 



