NOTES ON ZOOGEOGRAPHY. 



fully support this conclusion. There are five species of 

 Achatinella, one Partuliiia and two Laminellas. Three of 

 these are referable to Koolau species, and the others are so 

 clearly allied to several diverse species, belonging to groups 

 widely spread in the Koolau range, that they must be deriva- 

 tives from them. There is no endemic Waianaean strain of 

 Achatinellida', and from all indications it seems that this 

 family was lacking there until Pleistocene time. The old 

 Kaala massif, like Kauai, had a fauna of Amastrida. In the 

 diagram no. 2, in Vol. XXI, p. xx, Kaala might better have 

 been isolated from the Oahu-Hawaii island. These conclu- 

 sions have support from the distribution of plants. Mr. Charles 

 N. Forbes states of Kaala and its range that "its flora is as 

 distinct from the main range of Oahu as is the flora of any 

 separate island of the group' (Oec. Pap. B. P. B. Mus. V, 

 no. 4, p. 13, 1913). 



In the case of Maui, the two mountain masses are now 

 separated by a considerable width of low land, impassible 

 for land snails. It seems certain that the connection was 

 formerly more intimate. The number of identical or very 

 closely related species is quite considerable, and judging from 

 Mr. Thaanum's last expedition, it is likely to increase. The 

 isthmus must have been densely wooded, and probably it stood 

 at a decidedly greater elevation, to permit free exchange of 

 mountain snails. A rather recent subsidence of the whole 

 island is indicated by the absence of such an extensive pene- 

 plain as would result from the tremendous erosion of West 

 Maui, if that had been accomplished at the present level of 

 the island. 



The Kauaian satellite island Niihau will doubtless prove to 

 have had all of the widely spread genera of Kauai such as 

 Leptachatina, Succinea, Helicina, Tornatellina, Pupillidce, 

 Endodontidce etc. when its Pleistocene deposits are ex- 

 amined. A general account of the island and list of the plants 

 has been given by Mr. C. N. Forbes from notes made by Mr. 

 J. F. G. Stokes (Occ. Pap. B. P. B. Mus. V, no. 3 with map). 



Theories relating to the origin of the Hawaiian fauna have 

 been unduly influenced by the inferences of geologists con- 



