42 DIVERGENCE UNDER THE SAME ENVIRONMENT. 



The relative numbers in which these different variations occur are 

 roughly indicated in the following table, in which the numbers not 

 inclosed in parentheses correspond with the figures in Plate III, while 

 the number in parentheses below each one of these indicates approxi- 

 mately the relative frequency in which it was found. 



I 2 3456 78 9 10 II 12 13 



(200) (150) (100) (60) (30) (200) (200) (200) (200) (100) (200) (200) (200) 



14 15 l6 17 l8 IQ 2O 21 22 23 24 25 



(100) (60) (i) (200) (200) (200) (60) (30) (300) (45) (15) (15) 



The metropolis of Bulimella rosea is Wahiawa, where the most 

 abundant type of coloring is seen in figure 22, which is snowy white 

 with a pink lip. In Helemano district, the shells of this species are 

 somewhat smaller, with the lip more frequently white, and the body 

 of the shell not as snowy white as is usually the case in the metropolis. 

 Figure 2 1 is a comparatively rare variety of B. rosea, white throughout 

 and intergrading with B. ovata through a nearly white variety of the 

 sinistral form of that species, occurring in Kahana in the proportion of 

 perhaps one to a thousand of the normal specimens of the species. 

 Again, in figure 16, we have a very rare form connecting Bulimella 

 obliqua with Bulimella ovata. 



OAHU THE METROPOLIS OF THE AcHATiNEUvin^. 



The island of Oahu may be regarded as the metropolis of the Acha- 

 tinellidae, for on this island we find 8 of the 10 genera, while on Maui 

 and Molokai together we find 7 genera, and on Kauai 3 genera. Suf- 

 ficient attention has not been given to the land snails of Hawaii to 

 enable us to give a full report ; but I am told that there is an unusual 

 development of Succinea on that island, while the Achatinellidae are 

 but very meagerly represented. One explanation of the small devel- 

 opment on the island of Hawaii of the family of snails which is so 

 fully developed on the island of Oahu is found in volcanic eruptions, 

 which on the island of Hawaii have from time to time destroyed the 

 forests till recent years; while on the island of Oahu it is probably 

 hundreds of thousands of years since such complete destruction of the 

 necessary conditions of existence for these creatures has occurred. 



