LYROPUPA. 231 



e 2 . Whorls less convex, with more ribs ; 

 length 2.4 to 2.9 mm. 



L. haivaiiensis, 110. 11. 



dr. Basal fold rather weak or wanting ; Oahu, 

 Molokai, Lanai and Maui. 



e 1 . 15 to 17 ribs on the last whorl. 



f l . Palatal folds rather long; 

 Oahu. L. antiqua, no. 10. 



f. Palatal folds short; Maui. 



L. scabra, no. 14. 



e 2 . 19 to 25 ribs on the last whorl; 

 length 2 to 2.3 mm. ; Molokai, Lanai. 



L. sparna, no. 12. 



II. Shell dextral (Section Mirapupa). 



fi\ Lower palatal fold continuous, rather long, entering as far 

 as the upper palatal, its inner end slightly enlarged and 

 turned downward (pi. 22, figs. 2, 4) ; shells having the ex- 

 ternal appearance of L. perlonya. Molokai, Lanai, Kahoo- 

 lawe and Hawaii. L. kahoolcuuensis, 110. 15. 



'/-. Lower palatal fold very short or reduced to a low, callous 

 pad or tubercle ; one, or usually two strong tubercles or 

 short folds below the inner end of the upper palatal fold, 

 forming a vertical barrier (pi. 25, figs. 14, 15). 



fe 1 . Form cylindric, the last three whorls flattened in the 

 middle; three impressions on the back; ribs narrow, 

 generally flexuous. 



c 1 . Back having a hump below the middle of the 

 last whorl ; shell generally under 2 mm. long, 



L. micro,, no. 17. 

 c 2 . No dorsal or basi-dorsal hump. 



d\ Narrow, flexuous ribs, mostly continuous 

 and rather widely spaced ; Oahu. 



L. pcrlonga, no. 15. 

 d 2 . Very irregular, closer ribs ; Oahu. 



L. p. interrupts, no. 16#. 



d z . crowded, slender riblets; Kauai and 



Niihau. L. p. filicostata, no. 16&. 



