xxviii FAUNA HAWAIIENSIS 



variations under more normal conditions are very great, and it is presumably the parent 

 of the other species of its genus that are considered distinct and endemic. Both the 

 Koa and Ohia are of great importance to the fauna, since hosts of creatures are 

 dependent on them. The former probably supports the larger number of peculiar 

 forms, of which, no doubt, many have been exterminated by its extensive destruction. 

 Throughout this forest-belt ferns, both epiphytic and terrestrial, are most numerous and 

 varied, often covering the whole surface of the ground beneath the trees or clothing 

 the trunks of the latter. Here the tree-ferns acquire their greatest size and beauty. 

 The fauna connected with ferns is quite rich, not only tree-ferns but the lesser species 

 also yielding their own peculiar insects. In the Rhyncophorous beetles a number of 

 species of Proterhiniis are restricted each to a particular species of fern, and tree-ferns 

 support Heteramplms and Dryophthoriis. Small crickets of the genus Pai'atrigonidiuin 

 affect each their own special ferns, as do some Hemiptera (Heteropterous and Homo- 

 pterous) and larvae of various Macro- and Micro- Lepidoptera feed only on these. 

 Tree-ferns are a favourite resort of numerous Carabid beetles, and the dead fronds are 

 the home of Machilis and many other creatures. It seems probable that in the islands 

 the fauna attached to ferns is proportionately much more extensive than one usually 

 finds to be the case elsewhere. For this reason some of the endemic birds are constantly 

 to be found seeking for food on the stems and amongst the fronds, and some of the 

 land Molluscs are also very partial to them. 



It is not necessary to give a list of the trees and shrubs that form this compact 

 forest-belt, for herein are found species of nearly all the important genera of plants, 

 while many are altogether confined to it. Its components are very different in different 

 localities, the difference depending in many cases on the nature of the soil or of the 

 rainfall. In drier localities one will sometimes find a less dense and more varied forest 

 than in a closely adjoining and wetter district, or a wetter part of the belt may be more 

 varied in its vegetation than that at a higher elevation and with a lesser rainfall. Apart 

 from the Ohia and Koa already mentioned the following are very important trees or 

 shrubs to the student of the fauna : the arborescent Lobeliaceae, the Rutaceous Pelea 

 and Zanthoxyluin ; Cheirodendron and other Araliaceae ; the Rubiaceae generally ; 

 Pipturiis and other Urticaceae ; Myrsme (Myrsinaceae), Broussaisia (Saxifragaceae), 

 Elaeocarpus (Tiliaceae), Perrotetia (Celastraceae), the Leguminous Sopliora chrysophylla 

 and an endemic Rubus. However, most trees and shrubs of this belt are more or less 

 productive, and one may add to the above Eugenia sandwzcensis, the numerous species 

 of Pittosporum, Santalum, Myoporuin, Nothocestrum, Charpentiera, Pisonia and the 

 arborescent or woody Compositae. 



On the highest mountains towards the upper limits of the forest there is often 

 a very uniform flora, rich nevertheless in species of birds and insects. Acacia koa, 

 Sophora chrysophylla, and Myoporiun sandivichense sometimes form its chief com- 

 ponents. Lower down Metrosiderus interspersed with lesser trees such as Myrsine, 



