ACHATINELLA. 275 



The forms of this group which have been described as species 

 number not less than 53, besides several names for varieties. 

 Doctor Hartman (1888) reduced them to 15; Mr. Baldwin, in 

 his Catalogue of 1893, admitted 32; and Mr. Sykes, 1900, 

 enumerates 17 species with 13 varieties. The lists of 

 synonyms given by these authors differ very widely among 

 themselves, and still more from the synonymy proposed here- 

 in. My collaborator Doctor Cooke had worked out an ar- 

 rangement of all the forms under eight specific heads before 

 I took the group up. Using Cooke 's work as a basis, later 

 studies confirm nearly all of his results, but it appears neces- 

 sary to add A. swiftii and A. leucorraphe to the list of species, 

 with consequent rearrangement of the synonymy of other 

 forms. With some hesitation, specific rank has also been al- 

 lowed to the Waianaean A. concavospira, making 11 species 

 in all. 



It was hoped that characters might be found in the repro- 

 ductive organs which would aid to indicate specific boundaries, 

 but dissections of A. lorata, vittata simulans and mustelina 

 show no tangible structural differences. 



A consistent arrangement of the species in linear order is 

 impossible, as the group is formed of two parallel series which 

 merge together in the less specialized median species of each. 



The minor series consists of apexfulva, turgida and lorata,. 

 species in which the apex is never black or dusky. These 

 forms are confined to the Main range, but do not reach to 

 either end. 



In the greater series the tip of the apex is invariably dark 

 in some species (cestus, vittata, leucorraphe), and is variable, 

 either dusky or light, in others. The species are distributed 

 over the whole length of both the main and the Waianae 

 ranges. 



An alternative and probably better grouping may be sug- 

 gested. (1) Series of lorata, for A. lorata. (2) Series of 

 apexfulva, for A. apexfulva, turgida, swiftii, leucorraphe, 

 vittata, cestus. (3) Series of decora, for A. valida, decora, 

 mustelina, concavospira. See diagram on page 278. 



The distribution of the species, so far as positively known 



