38 DIVERGENCE UNDER THE SAME ENVIRONMENT. 
the most divergent species that have been chosen, but the most closely 
related of those found on the different islands. 
In the case of arboreal species, the isolation between those inhab- 
iting the forests of East Maui and those inhabiting the forest of 
West Maui is almost as complete as if they inhabited separate islands; 
for the open grass land separating the two masses of forest-covered 
mountains is as complete a barrier against direct migration as would 
be a salt-water channel. ‘There is, however, a somewhat better 
chance of transportation by human agency across grass land than 
across an equal width of water. 
Carelia is always dextral in form; and I think it is terrestrial in its 
habits. Amastra and Leptachatina, which are almost always found 
on the ground, are with extremely rare exceptions dextral in form; 
while of the arboreal genera, Newcombia and Laminella are almost 
always sinistral, and Auriculella, Apex, and Partulina have some spe- 
cies constantly sinistral, others constantly dextral, and others that 
assume eitherform. Achatinella and Bulimella (represented in Plates 
If and ITI), are constantly arboreal in habits, and both dextral and 
sinistral in the forms assumed. 
The following abbreviations are used in the ‘‘Notes”’ on the species 
' given in Plates I, IJ, and III. 
Fer. = Ferussac; Gk. = Gulick; Migh. = Mighels; Nwe. = Newcomb; Pfr. = 
Pfeiffer; Rv. = Reeve; Sm. = Smith; Swn. = Swainson; D = dextral in form; 
S = sinistralin form; D > S = the majority are dextral; S >> D = the majority 
are sinistral; S — Ba = sinistral with the exception of about 1 in 500. 
NOTES ON THE SPECIES. 
Fic. 1. Carelia cocklea (Rv.) D. From the island of Kauai. Examination of 
the organs will probably place it with the Achatinellide. 
Fic. 2. Amastra nucleola (Gould) D. From Waiole, Kauai. 
Fic. 3. Auriculella auricula (Fer.) D > S. This species, like others of this 
genus, is found on the leaves of trees and shrubs. Its habitat is the eastern por- 
tion of the forest region of the island of Oahu. ‘This specimen is from the valley 
of Palolo. 
Fic. 4. Apex apicatus (Nwe.) D > S. From Wahiawa, Oahu. Also found in 
Helemano and Ahonui. 
Fic. 5. Leptachatina fumosa (Nwe.) D. Found on the ground under dead 
leaves, in damp forest regions from Nuuanu to Palolo, on the island of Oahu. This 
specimen is from Palolo. 
Fic. 6. Laminella sanguinea (Nwe.) S. Found in Helemano and Wahiawa and 
the intervening regions on the island of Oahu. This specimen is from Helemano. 
Fic. 7. Laminella citrina (Migh.) S. From the island of Molokai. 
Fic. 8. Laminella tetrao (Nwe.) S. From the island of Lanai. 
Fic. 9. Laminella venusta (Migh.) S. From Lahaina, West Maui. 
Fic. 10. Laminella bulbosa (Gk.) S. From Kula, East Maui. 
Fic. 11. Partulina dubia (Nwe.) D. This is a rare species distributed over a 
number of valleys of the island of Oahu from Waianae to Kalihi. This specimen 
