AMASTRA, OAHU. 217 



anu and Manoa valleys, baek of Honolulu ; where luteola came 

 from is not known; and spirizona is the only species known 

 to be from any other district. Since exactly typical shells 

 occur in the Waianae mountains, especially up Waianae valley 

 on Mt, Kaala, this valley may be considered the type locality. 



There is some variation in proportions, chiefly between the 

 following extremes : 



Fig. 18. Length 21.3, diam. 10.3, aperture 9 mm. ; 7 whorls 

 (Waianae). 



Fig. 17. Length 19, diam. 12, aperture 9.5 mm. ; 6!/o whorls 

 (Lihue). 



Achatinella acuta Swainson was based upon specimens from 

 the northern range having the spirizona coloring, such as 

 occur mingled with nigroldbris in Kawailoa valley, and doubt- 

 less interbreeding with nigrolabris, which is the dominant 

 form ; as usual in such Mendelian hybrid races, the mutant 

 dominates. Swainson 's type was a shell in which there is a 

 deep sinus below the columellar lamella, such as we have 

 figured in pi. 40, fig. 16, from Kawailoa. This feature is quite 

 variable, both in spirizona and nigrolabris. The basal lip is 

 not quite so deeply arcuate as in spirizona. Properly speak- 

 ing, the name A. acuta is not a synonym of spirizona, but be- 

 longs to the spirizona X nigroldbris hybrid race ; see below. 



It may be mentioned here that all of Swainson 's Achati- 

 nellas were collected by Lord Byron, an account of whose 

 voyage has been published (Voyage of H. M. S. Blonde to 

 the Sandwich Islands in the years 1824-1825. London, 1826) . 

 The only Oahuan port visited by the Blonde was Honolulu. 

 All of the Acliatinellidcc brought home were strung on a neck- 

 lace, which wa:s evidently made in Kawailoa valley, the species 

 and color-forms being all such as occur in that neighborhood, 

 none of them being from the Waianae mountains, or from 

 eastern Oahu. Dr. Newcomb has already noted this fact, 



48a. A. s. nigrolabris Smith. PI. 35, figs. 10 to 15. 



"Shell dextral, globose-conic, perforate (the perforation 

 sometimes covered by callus), little shining, longitudinally 

 rugose (hardly spirally) striate; deep black-brown, encircled 



