HYATT: GENEALOGY OF ACHATINELLID^E. 389 



Part, hayseldeni Bald., is a shell having an apex like vir- 

 gulata, but becoming uniform light chestnut brown in later 

 stages and having bulimelloid aperture and columella. One 

 shell in Cooke's collection (No. 2204) has two keels until a 

 late age and another does not lose the keel entirely even 

 in extreme age. The shells of the sub-series virgulata are 

 uniform and banded, but the young in nepionic stages are 

 invariably banded with white on the shoulders and have 

 brown sides. 



Partulina mighelsiana Pfr., constitutes a group of itself, 

 which we may call the mighelsiana series. The apex of Par- 

 tulina mighelsiana Pfr., has the colors of Achatinella and 

 Bulimella, but the form is more slender and more acute, and 

 like that of typical Partulina. There are no signs of zigzag 

 or marbled patterns, but instead the banded patterns prevail 

 as in Achatinella. In one species, Part, mighelsiana of 

 Molokai, the aperture and columella are constantly similar 

 to those of the Achatinella-like shells of the bella series, and 

 in subpolita of Molokai the form and characters and apex are 

 precisely intermediate between mighelsiana and polita. I 

 have examined altogether 53 specimens of Partulina mighel- 

 siana, including several varieties, without finding in the young 

 any trace of the barred or marbled pattern common in de- 

 generate forms of Partulina. 



In Cooke's collection there is a fine series of varieties of 

 mighelsiana that exhibit intermediate forms between this 

 and Achatinella polita in full-grown shells. In this, and 

 especially in Gulick's collection, the only characters that 

 separate the young of some specimens are the somewhat lighter 

 color of the dark sides of the apex and the brown band on 

 the base; there is one shell in Gulick's collection in which 

 this last is the only difference, the apex having white shoulder 

 band and dark side precisely as in nepionic stage of A. polita. 



In quite a number of Cooke's shells the white shoulder is 

 present in the young and the side of the volution underneath 

 is darker, and it is obvious in these characters and in the 

 smooth, highly polished shell, that the affinities with polita 

 are very close and indicate a common origin for both species. 



