LYROPUPA. 231 



e~. "Whorls less convex, with more ribs ; 

 length 2.4 to 2.9 mm. 



L. hawaiiensis, no. 11. 



d 2 . Basal fold rather weak or wanting ; Oahu, 

 Molokai, Lanai and Maid. 



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



f 1 . Palatal folds rather long; 

 Oahu. L. antiqua, no. 10. 



f 2 . 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). 

 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. perlonga. Molokai, Lanai, Kahoo- 

 lawe and Hawaii. L. kahoolavensis, no. 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). 



& 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. micra, no. 17. 

 c 2 . No dorsal or basi-dorsal hump. 



d 1 . Narrow, flexuous ribs, mostly continuous 

 and rather widely spaced ; Oahu. 



L. perlonga, no. 15. 

 d 2 . Very irregular, closer ribs ; Oahu. 



L. p. interrupt^ no. 16a. 



d*. crowded, slender riblets; Kauai and 



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



