INTRODUCTION cciii 



fact occurs with it on the island of Lanai. Though recorded only from that island, it 

 may not improbably be found on Molokai or Maui or on both of these islands. 



AcANTHiiDAE. — There are two distinct forms of Acanthia, and each of these 

 exhibits striking variation, or it may be that there are several closely allied species 

 related to each of these two forms. However that may be, there is certainly great 

 variation in individuals of a single species in superficial appearance. The diversity of 

 habits shown by these Hawaiian species is of considerable interest. Both frequent the 

 margins of mountain streams, but are found quite away from these, running on the 

 ground in damp shady places, in thick forest. They are also at home in damp rocky 

 places in open parts of the mountains. On one occasion on Hawaii, when climbing a 

 tree to collect certain species of beetles, I found two or three specimens of Acanthia 

 running on the trunks, high above the ground, a habit, as Kirkaldy informed me, quite 

 unique. Curiously enough two of these arboreal individuals, taken together, had no 

 superficial resemblance to one another, though, I think, clearly of one species, nor do 

 they differ from examples found running over a wet, rocky cattle trail on Molokai, 

 where the insect showed similar variation. It is a remarkable fact that while in some 

 localities a number of individuals of Acanthia may be taken together and show no 

 great variation, in others, individuals will occur, which differ very greatly amongst 

 themselves. Nymphs are often met with in the same localities as the adults, some- 

 times in greater numbers than these, from which they differ greatly in head and thorax, 

 the former with the eyes being only about as wide as the front margin of the latter and 

 closely adapted to this. Both A. exulans and A. oa/mensis are flightless, the wings of 

 the former being much smaller and shorter than the tegmina and reaching about to 

 the middle of the abdomen. Those of A. oa/mensis are still further reduced, and 

 there is evident variation in examples from different localities, which may possibly be 

 specific. 



CoRixiDAE. — This family is represented only by Corixa blackhirni White, a 

 species not known from elsewhere. It is very widely distributed on the lowlands of 

 the islands, inhabiting salt-water pools as well as ponds of fresh water. It comes to 

 lieht at nisfht sometimes in considerable numbers. 



NoTONECTiDAE.— Represented only by Buenoa pallipes, a foreign species. It is 

 equally abundant near sea-level and in ponds on the mountains at an elevation of at 

 least 3000 ft., being generally distributed. 



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