HYATT: GENEALOGY OP ACHATINELLID^E. 397 



In C. bicolor there is a very minute perforation in the 

 neanic stage and there are indications in another individual 

 shell of the presence of a somewhat larger perforation. The 

 columella in [Cyclamastra] is at first incomplete in the young 

 then becomes complete and remains complete, the umbilicus 

 being open throughout life. 



In Kauaia the history is similar to that of Carelia in the 

 young, but the columella has a long straight ventral or inner 

 deposit, and during the period or stage of the completed 

 columella the umbilical opening is small and similar to that 

 of the Amastra rugulosa group of Kauai. In a more ad- 

 vanced age such as the ephabic and gerontic stages, the 

 columella again becomes solid, the umbilical opening closes, 

 and the deposits are less, and are plastered directly against 

 the axis. 



The Amastrae of Kauai have a columella which is long and 

 straight in shells that retain an open umbilicus ; and the aper- 

 ture in such examples is similar to that of [Cyclamastra] 

 which never closes its umbilicus, and to the young of Kauaia 

 during the stage when the umbilicus is open. In shells that 

 close up the umbilicus, a variation that occurs apparently in 

 species having an open umbilicus, the columella and aperture 

 resemble that of Kauaia in its older stage and after its um- 

 bilicus closes. 



In all these species the thick brown periostracum is a 

 marked characteristic, and a tendency to put on more lively 

 colors is only shown in a few species by bands, etc. 

 [Cyclamastra] is obviously the nearest to the ancestral form 

 of Amastra. This has an open umbilicus, and form both of 

 spire and aperture and columella which is more or less re- 

 peated in the young of all other species in the neanie stage. 



The gradation appears to be as follows: [Cyclamastra'} is 

 directly connected with Kauaia. Kauaia is similar to it 

 only in the young. Armiella is similar to Kauaia and 

 descended from it or from some common ancestor, but hav- 

 ing two longitudinal ridges on the dorsum, and a distinct 

 aperture. Amastra is derived from [Cyclamastra} which 

 the species resemble during a part or the whole of their 



