430 



The Jumping Plant Lice (Family Psyllidae) of the 

 Hawaiian Islands. 



A Study in Insect Evolution. 



BY D. L. CRAWFOED. 



The fauna and flora of the Hawaiian archipelago are of 

 more than common interest because of the great isolation of 

 these islands from other land bodies and also because thev 

 appear to have held such an isolated position for a very great 

 lapse of time — perhaps since the Paleozoic era. 



The native vertebrate fauna is exceedingly limited, an 

 endemic bat being the only mammalian species surely native. 

 A considerable number of birds occur, most of the species 

 having developed here from a few early immigrants. 'No 

 endemic reptiles nor amphibia are found here, with the pos- 

 sible exception of a species or two of skinks and these prob- 

 ably were brought in by human agency. 



Among invertebrates, certain groups of land shells (Mol- 

 lusca) and insects are the most abundant, and at the same 

 time present some very remarkable features. First among these 

 remarkable features is the large number of endemic species 

 representing a comparatively small number of groups. That 

 is to say a comparatively small number of insect and molluscan 

 species have in the more or less remote past chanced to arrive 

 here and establish themselves and, rejuvenated by the new 

 and favorable environment in which they found themselves, 

 have split u]i into a large number of derivative species and 

 even genera, and in several cases even endemic families — one 

 endemic family of beetles (Proterhinidae), one of land shells 

 (Achatinellidae), and one of birds (Drepanididae). This of 

 course indicates that plant immigrants had already established 

 a flora of the Islands upon which these animal immigrants 

 found sustenance. 



A second remarkable and sigiiificant feature of the endemic 



Proc. Haw. Ent. Soc, III, No. 5, April, 191 



