PARTULINA, LANAI. 87 



gulated in the middle and semicarinated. Aperture ovate; 

 columella ending in a tortuous, obtuse, dentiform plait ; outer- 

 lip anteriorly produced, strongly marginate within. Color 

 pale yellow, aperture white internally. A straw-colored, coni- 

 cal species, with the last whorl partially surrounded with an 

 elevated keel " (Newcomb). No dimensions given. 



Lanai (Newcomb, Thaanum et al.) ; mountains at high ele- 

 vations (Perkins) ; at the crest of the main ridge, extending a 

 little way down (Thaanum). 



Achatinella semicarinata NEWC., P. Z. S., 1853, p. 156, pi. 

 24, f. 76, 1864. PFB., Monogr., iv, 532. Achatinella varia- 

 bilis var. semicarinata SYKES, Fauna Hawaiiensis, p. 320. 



This species differs from P. variabilis fulva by its decidedly 

 broader contour and dextral coil. The glossy surface shows 

 only weak traces of spiral striation. The aperture, lip-rib 

 and columella are white, or in the darkest shells, the interior 

 is faintly pink tinted. The early whorls are the color of the 

 shell in most specimens, but in some they show distinct dark 

 bands. Embryo shells usually show bands, though not always 

 so distinct as in fig. 15, an embryo from a cream-colored 

 mother. The color of adults varies from white to tawny or 

 light orange-rufous. The acute earina may extend half 

 way around the last whorl, or it may not be developed at all 

 there, ending on the penultimate whorl. Usually it extends 

 part way across the front of the shell. The axis is perforate. 

 In a series of 23 from Thaanum and Baldwin, all are dextral. 

 Newcomb 's type figure is copied in pi. 21, fig. 13. It repre- 

 sents the most strongly carinate form. The size varies. 



Length 18, diam. 12 mm. 



Length 17.5, diam. 11 mm. 



Length 16, diam. 11 mm. 



Length 15, diam. 9.5 mm. 



Mr. Sykes ranked semicarinata as a variety of variabilis 

 on account of the difficulty he experienced in endeavoring to 

 separate it from fulva. " Mr. Perkins remarks that ' the 

 broader form with ridge more raised is from higher eleva- 

 tions. ' It appears to be gradually replaced by the form fulva 

 at lower altitudes." I have here retained semicarinata as a 



