THE NAUTILUS. 



her of rib-like irregular ridges". P. pennsylvanicus Pi!s. (Proc. 

 Acad. Nat. Sci. Phil., p. 22, 1894) is described as being 

 " smaller and less distinctly marked than P. carolinensis" and 

 "having the jaw strongly ribbed", a description which coulcf 

 not be applied to P. rushi. 



CLIMATIC CONDITIONS AS INDICAT3D BY LAND SHELLS OK THE 



ISLAND OF OAHU. 



BY J. J. GOUVEIA. 1 



Since the early part of 1913 the writer and his brother A. 

 Gouveia have been engaged in making a collection of Hawaiian 

 land shells, both ground and tree. We have accumulated spec- 

 imens of shells from nearly all valleys and ridges on the island 

 of Oahu. We have complete data as to the exact locality and 

 habits, so it can be seen that the writer has a good proof, from 

 his series, of Gulick's theories of segregation or isolation. This 

 idea has been written and followed out by many other collectors 

 and students until it is well known in the scientific world. One 

 of the best examples of this is seen in Dr. Cooke's paper on 

 Achatinella multizona. 



DISTRIBUTION OF Achatinella cestus FROM MANOA-PALOLO RIDGE 

 TO WAILUPE-NIU RIDGE. Achatinella cestus (Newcomb) is found 

 mostly on lehua or one of its related plants having a rather 

 large dark green and glossy leaf, on leie, Opiko and Lantana, 

 and nearly always under leaves, with the exception of the 

 Wailupe-Niu locality where they are found mostly on Lantana 

 stems. They are nearly always found sealed. The only time 

 they are found extended is when they are disturbed by wind or- 

 rain or accidentally brushed off, so they must be nocturnal as 

 Dr. Cooke surmises (1). 



They are very variable in color from white to very dark 

 brown. They are lighter on the western part of the range and 

 become darker towards the eastern part. The greater part of 

 these shells have a white border band (2). 



1 Contribution from the Gulick Natural History Club. 



