28 



THE FAUNA OF HAWAII 



The Hawaiian animals also show strong evidences of relationships 

 with those of the Southern Pacific countries, there being only a small 

 number of species that point to a derivation from American sources. 



MOLLUSCS 



The molluscan fauna is an extremely specialized one, and the land 

 snails, which show a remarkable diversity, have been collected assidu- 

 ously. According to Pilsbry, these are all ancient types, whose modern 

 representatives are largely confined to Polynesia. More remotely related 

 are species of the adjacent Asiatic regions. 



"There is a marked absence of the modern land snails. There are 

 no Helicidae and no slugs, in a word, none of the groups that have con- 

 stituted all known continental faunas since the Eocene." 



Pilsbry contends that these primitive snails represent an ancient 

 fauna which has survived from a time when Hawaii was part of a conti- 

 nental area, connected with the Polynesian area to the southwest, where 

 their nearer relatives are now found. "They represent early branches of 

 the phyletic tree of the land snails." 



Pilsbry thinks it extremely unlikely that these snails have been 

 brought from outside to the islands, for if carried either by birds, by 

 drift, or any other agency, it is remarkable that none of the modern snails 

 have succeeded in reaching Hawaii. We must assume that transporta- 

 tion must have ceased before Tertiary time, for "otherwise it seems un- 

 accountable that all dominant Tertiary snails of the continental areas are 

 absent." 



Pilsbry concludes that the distribution of the snails within the archi- 

 pelago points to a former connection of all the islands into one large land 

 mass. As a result of subsidence the islands became separated, Kauai 

 being the first to become isolated. 35 



INSECTS 



The total number of insects known from Hawaii is about 3,325," 

 of which 2,740 are supposed to be really indigenous. There is the usual 

 very high percentage of endemism, and a majority of the species are 

 related to Australasian and Indo-Malaysian types. 



25 "Manual of Conchology," Introduction, p. xvii. 



26 Perkins, R. C. L. : "Fauna Hawaiiensis," 1, Introduction, p. xii. 1913. 



