38 AMASTRA. 



A. HUMILIS MOOMOMIENSIS P. & C., n. subsp. PL 7, figs. 9 to 14. 



Differs from A. kumilis chiefly by the much smaller, or 

 often obsolete columellar fold. The shape is usually more 

 slender and elongate. 



Length 20.5, diam. 8.3, aperture 7.5 mm., whorls 7y%. 



Length 21.3, diam. 9 mm. 



Length 19.5, diam. 9 mm. 



Length 18, diam. 8.8, aperture 6.3 mm. ; whorls 7. 



Molokai : Pleistocene of the sand dunes of Moomomi, around 

 base of the bluff, Cooke and Pilsbry, 1913. Cotypes no. 

 110594 A. N. S. P. and in Bishop Mus. 



These shells dot the sand in the "draws' 7 or swales of the 

 dunes. In many places they may be scooped up by thousands. 

 The loose ones are mostly etched by the blowing sand, but 

 where the red-earth is exposed they occur imbedded, and show 

 the irregular striation of recent humilis. The various stages 

 in decadence of the columellar lamella are shown in the fig- 

 ures. Occasionally the surface is somewhat malleate, and in 

 some shells a tawny stain at the summit tells of the dark apex 

 of the living shell. 



Moomomi is a shallow bay on the north coast at the end 

 of the great escarpment running north from Mauna Loa. 

 In some places the calcareous sand has been consolidated and 

 stands in cliffs, carved into shelves and points by the wind. 

 The soft layers in this formation are good collecting places 

 for the small and minute forms. The shell-bearing layers 

 begin about 20 ft. above sea level, and run up to about 600 ft. 



The presence of great numbers of fragile shells, Succinea, 

 Endodonta, Philonesia, Tornatellinidce and Pupillidce show 

 that the snails were buried where they lived. They indicate 

 decidedly humid conditions and the presence of forest. Such 

 conditions are now found eastward a third of the island's 

 length from Moomomi, at elevations of over 1000 ft., but at 

 present nowhere in the western half of the island. Here, as 

 in Kahoolawe and Oahu, there is conclusive evidence of a 

 Pleistocene climate far more humid than that of today. 



Living A. humilis was taken by Dr. Cooke and myself in a 

 ravine east of Makolelau house. 



