390 HYATT: GENEALOGY OP ACHATINELLIM. 



In A. polita in the Cooke collection (No. 2014), one shell 

 has the band on the base and looks decidedly like a transition 

 or a hybrid between polita and mighelsiana. This has also 

 the white young of mighelsiana with the nepionic colors of 

 polita and has the dark inner rim to the aperture so often 

 found in mighelsiana. Cooke has placed it with polita, and 

 in this I agree with him. 



Partulina variabilis Series: These are Bulimelline forms 

 with the narrow acute flat-sided spire of Partulina. In varia- 

 bilis of Lanai, the callus or shield is present only in the larg- 

 est shells and very often absent at all stages. This is transi- 

 tional in others in which the aperture is constantly >buli- 

 melloidal. It is apparently an offshoot of P. mighelsiana and 

 so far as I can see does not connect with any other species 

 although coming very close to some in its general aspect. 

 The species are as follows: Partulina variabilis Newc., 

 P. lactea Gul. of Lanai, and Part, nivea Bald., dolei Bald., 

 and eburnea Gul. of East Maui. 



Relationship between Partulina and Achatinella: The con- 

 clusion seems unavoidable that all true Partulina? exhibit in 

 their young stages direct affinity with Achatinella, and that 

 the genus was derived from Achatinella that migrated to 

 Molokai and probably began its existence on that island, for 

 I have traced direct transitions from Achatinella polita to 

 adults of A. polita in Cooke 's -collection and the young in 

 Partulina mighelsiana in Molokai. These were found in 

 other collections showed very close affinities. 



Three species of Achatinella, A. bella Rve., polita Newc., 

 and subpolita, occur outside of Oahu on the island of Molokai. 

 These four species cannot be distinguished from Achati- 

 nellae of Oahu by any character so far as I could ascertain, 

 for the columella is very similar to that seen in many species 

 on Oahu. 



In East Maui there are three species of Achatinella, A. 

 anceyana Bald., nattii Bald, et Hart., and porcellana Newc. 

 In all three of these species there is the same tendency ob- 

 servable in varieties to imitate the aperture of Partulina while 

 others retain the thinner apertures and columellae of true 



