HYATT: GENEALOGY OF ACHATINELLID/K. 395 



series ; and its nearest affines now living are PartuUnella 

 dwighti of Molokai and P. crassa of Lanai. The more elon- 

 gated species of this series are Perd. theodorei Bald, of 

 Molokai. This makes genetic connection with P. ornata 

 Newc., of West Maui and P. mauiensis Newc., of Maul. 

 These species have no tooth-fold or only very slight spiral 

 ridges on the columella and in the last three the forms are 

 much elongated and more turritelloidal than in P. Helena. 

 The parallelism with Carelia is very marked in form as well 

 as in the toothless columella. 



The highly specialized habitat of helena is stated by New- 

 comb to be within the coil of the Ti (Dracaena) leaf at the 

 point where it starts from the stem, is exceedingly suggestive 

 when taken in connection with the dwarfed aspect of this 

 species and others of the same genus supposed to have origin- 

 ated from some such ancestor as P. proximo,. [P. helena or- 

 dinarily lives on leaves and twigs of numerous shrubs and 

 trees, H. A. P.] 



Relationship bettveen Newcombia and Perdicella: The 

 genus Newcombia was described by Pfeiffer and the first 

 species mentioned under this name is Achat. helena Newc., 

 from Molokai. Pease placed this species, and the two follow- 

 ing in other genera, and used the fourth species, Newcombia 

 cumingi Newc., as the type. If the author and Mr. Baldwin 

 are correct in their translation of the facts, this action of 

 Mr. Pease appears justified if the name can be maintained 

 for the extremely elongated, rough, sinistral shells having an 

 umbilical perforation and no specialized tooth-fold, but having 

 .a callous deposit or swelling at the base of the columella. 

 These three characters are always found in Newcombia 

 cumingi Newc. of West and East Maui and Newcombia new- 

 combiana Pfr., and plicata Mighels, cinnamonea, sulcata Pfr., 

 and canaliculata Baldwin, all of which are from Molokai, the 

 metropolis of the genus. The genus is certainly limited to 

 Molokai and Maui. Its absence on the adjacent island of 

 Lanai is very remarkable and interesting but entirely in 

 character with its highly specialized form and unique 

 ornamentation. 



