232 LYROPUPA. 



fe 2 . Form ovate or cylindric-tapering, or cylindric with 

 conic summit; whorls convex; ribs strong, arcuate, 

 about 15-16 on the last whorl; diam. equal to or ex- 

 ceeding half the length. 



c 1 . Last half whorl having deep impressions; 

 length 2 to 2.3 mm. 

 d 1 . Species of Oahu. 



e 1 . A prominent, straight basal crest 

 (pi. 24, fig. 2) ; lower palatal fold 

 a diffuse tubercle. 



L. ovatida, no. 18. 



e 2 . No distinctly differentiated basal 

 crest; lower palatal a short, high, 

 oblique fold. 



L. plagioptyx, no. 19. 



d 2 . Species of Hawaii. Lower palatal and 

 basal folds developed as oblong tubercles ; 

 back humped at base. 



L. o. kona, no. 18. 



c 2 . Last half whorl having two slight impressions, 

 sometimes obsolete; lower palatal a very low, 

 callous tubercle ; length 2.75 mm. Hawaii. 



L. cyrta, no. 20. 



Z> 8 . Form broadly oval, compact, the Avhorls short, con- 

 vex, the last whorl with 25-30 ribs, and one or two 

 impressions on the back ; length 1.9-2.2 mm. 



c 1 . Diameter about 70 per cent of the length; 5 

 whorls ; aperture contained 2% times in length 

 of the shell. L. cubana, no. 21. 



c 2 . Diameter about 58 to 65 per cent of the length ; 

 5% whorls ; aperture scarcely one- third length 

 of shell. L. thawmasia, no. 22. 



Group of L. lyrata. 



Sinistral Lyropupae characterized by a strong, long, angu- 

 lar lamella, and by minute spiral striaB between and on the 

 strong ribs. There are two series belonging to this group. 



