232 LYROPUPA. 



fo*. Form ovate or cylindric-tapermg, or eylindric 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. ovatula, no. IS. 



e' 2 . No distinctly differentiated basal 

 crest; lower palatal a short, high, 

 oblique fold. 



L. plagivptyx, 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> 5 . Form broadly oval, compact, the whorls short, con- 

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

 impressions 011 the back ; length 1.9-2.2 mm. 



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

 whorls; aperture contained 2i/> times in length 

 of the shell. L. ciibana, 110. 21. 



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

 51/2 Avhorls ; aperture scarcely one-third length 

 of shell. L. tliaumasiu, no. 22. 



Group of L. lyrata. 



Sinistral Lyropupae characterized by a strong, long, angu- 

 lar lamella, and by minute spiral stria3 between and on the 

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



