ACHATINELLA, SECT. ACHATINELLASTRUM. 181 



smooth, with unexpanded lip, which is but slightly or not 

 thickened within; columellar margin not raised or thickened 

 on the face. 



Type, A. producta Reeve. Distribution, Oahu, chiefly on 

 the Main Range. 



This is the most generally distributed group of Achatinella 

 In many places it is found on the northern side of the main 

 range, and in a doubtless more humid time of the Pleistocene 

 it lived down nearly to sea level. In the Waianae range there 

 are a number of colonies, but all excessively small, and situ- 

 ated on the inland slope. 



Achatinellastrum is related to Bulimella through such 

 species as casta and sowerbyana, where the sectional borders 

 are debatable. Such forms seem to be the least changed 

 descendants of the ancestral common stock. No point of con- 

 tact with the section Achatinella (Apex) is traceable among 

 the recent species. 



Achatinellastrum is more prolific in color-mutations than 

 any other group of the family. The number of patterns runs 

 into hundreds. About 72 names have been applied to sup- 

 posed species. This number was reduced to 49 by Mr. Bald- 

 win in his Catalogue of 1893. Mr. Sykes, 1900, recognized 

 35 species and 3 varieties. In the following account 17 

 species and 14 subspecies are admitted, two species and three 

 subspecies being new. 



In the section Achatinellastrum, it is not likely that any 

 conservative zoologist having adequate collections and data, 

 would recognize more than seventeen species; but if the evi- 

 dence is critically examined, it appears that there are pheno- 

 typically intermediate forms hybrids or undifferentiated 

 remnants of the parent stock between many of the conven- 

 tional species. It would be quite possible to reduce the ' ' good 

 species ' ' to nine or ten. 



Thus, in the eastern end of the Main Range, we have a 

 chain of connected forms in (1) A. ph&ozona fulgens ste- 

 wartii vulpina. A little apart from them stands (2) A. 

 buddii. This is succeeded by the form-chain of (3) A. bellula 

 casta juncea. Allied, but not connected are (4) A. juddii 



