AMASTRA, HAWAII. 309 



type lot have longitudinal zigzag stripes, which sometimes 

 partly anastomose to form a net-work, as in fig. 19. 



AMASTR^E OF HAW AH. 



In Hawaii Amastrae have been found from the Kohala 

 Mountains and the northern slopes of Mauna Kea, district of 

 Hamakua, to the southeastern slope of Mauna Loa in Kan 

 district. They also occur with many other land shells as 

 fossils in Holocene deposits at the upper edge of the Waimea 

 plains, at about 3000 ft. elevation, at Mana and Palihou- 

 kapapa, in northern Hamakua. " At Mana the shells occur 

 in horizontal strata two or three inches thick and under a 

 deposit of about a foot of humus. ' ' At Palikoukapapa they 

 are in ' ' pockets, sometimes containing a bushel or more of 

 shells. ' ' Similar deposits occur above Honakaa, and they are 

 probably widely spread. The region is said to have been cov- 

 ered with fallen tree-trunks less than fifty years ago. Our 

 knowledge of the deposits is due to a paper by Mr. H. W. 

 Henshaw, Journal of Malacology, xi, Sept., 1904, p. 56, and 

 to shells sent by Mr. Baldwin. 



The Hawaiian species belong to two groups, both of Amas- 

 trelloid type. The flavescens series is not distinguishable by 

 the shell from typical Kauaian Amastrella. The melanosis 

 series differs by its striate embryo and tendency to angula- 

 tion in the later stages, and forms a specially Hawaiian modi- 

 fication of Amastrella. 



We have elsewhere alluded to the possibility that A. luteola 

 Fer. may turn out to be an Hawaiian species of the flavescens 

 series. 



Key to Hawaiian species of Amastra. 



I. Shell sinistral. A. sinistrorsa, no. 104. 



II. Shell dextral. 



a. Embryonic whorls nearly smooth, marked with faint 

 growth-striae only; shell rather solid, with thin 

 yellow or brown cuticle. 



&. Diameter about two- thirds the length; length 

 about 12 mm. A. hawaiiensis, no. 110. 



