ACHATINELLA BYRONII. 133 



and because there are differences in 'the patterns and colors, 

 I am recognizing the forms from the northward- side, collec- 

 tively, as a species (A. decipiens} distinct from those on the 

 south side of the range. The decipiens forms 'all appear to 

 be more closely related to one another than any of them are 

 to forms from the other side of the range, They seem to form 

 a parallel series to the latter. In both series there are smooth 

 forms in the west, corrugation becoming progressively more 

 emphatic eastward. In both series the western forms are in- 

 variably dextral, and sinistral forms occur in the east. This 

 correspondence would suggest communication across the 

 range, but the coloration is against that explanation of the 

 parallelism. From northwest to southeast the forms are ar- 

 ranged thus: smooth, dextral forms above (westward), rough, 

 sinistral forms below (eastward). 



kaliuwaaensis 



pulcherrima 



byronii decipiens 



rugosa corrugata, torrida 



nigricans 



Dr. C. Montague Cooke considers decipiens with its varieties 

 to be a subspecies of 'byronii. In retaining A. pulcherrima as 

 a species, I am following Dr. Cooke 's counsel, although I have 

 some doubt whether it should be given higher rank than a sub- 

 species of A. 'byronii. It is a case where there are numerous 

 local forms the variations of which overlap more or less, and 

 whether they 'are ranked as forms of one species, or are more 

 or less arbitrarily -assorted into several, is a matter of conveni- 

 ence in referring to the forms. The series shows such diver- 

 sity of differentiation that it would be rather meaningless to 

 lump all of the races under the one name, A. byronii. 



Practically all of the Newcomb 'and Grulick shells were taken 

 at low levels, 'chiefly in places where there are now no forests. 

 The modern collector in this part of Oahu rarely finds tree- 

 snails below the forest fence, which follows the 1,000 ft. con- 

 tour from Waimea to Moanalua. 



4. A. BYRONII (Wood). PL 27, figs. 1 to le, 3. 



The shell is dextral, imperf orate ; pyramidal-conic with ob- 



