INTRODUCTION xxv 



most of the species that are attached to the coasts also range inland over the plains or 

 ascend the dry and bare lower slopes of the mountains. They are xerophilous rather 

 than strictly littoral, and some of them even reappear in the dry open country above 

 the forest-line and rain-belt, even at elevations above 7000 ft. Some, however, if not 

 absolutely confined to the region of littoral plants, yet never wander far inland. These 

 include a number of endemic bees and wasps, which visit the flowers of such plants as 

 Vitcx trifolia, Scaevola kocnigii, Tribuhts, Waltheria etc., the wasps finding their prey 

 amongst these and other sublittoral vegetation, such as species of Sida, Lipochaeta and 

 foreign weeds. The Otiorhynchine beetle Rhyncogomis vestitus is attached to Vitex, 

 the endemic moth, Pyrausta iitorea, to Scaevola, while the caterpillars of a few Noctuid 

 moths and some Hemiptera (both Heteropterous and Homopterous) feed on grasses 

 and low flowering plants that grow in the sand. On the whole the littoral fauna 

 appears to be at any rate less poor than its flora. 



On the leeward side of the islands, owing to the comparatively small amount of 

 rainfall and (usually) the absence of any heavy rains during the greater part of the 

 year, the vegetation of the coastal region and lower mountain slopes is for the most 

 part dried up, and only after heavy rains does the verdure reappear. At the present 

 time, however, numbers of xerophilous plants, introduced by man, do much to lessen 

 the arid appearance of the lowlands. Chief of these is the algaroba or mesquite 

 {Prosopis), the most valuable tree ever imported into the islands. In some of the 

 driest coastal districts it now forms quite a forest-belt, affording food and shelter to 

 cattle and other animals, and an abundance of excellent firewood. An Opuntia of 

 very early introduction, a mimosa [Acacia farnesiana) and Lantana camara are very 

 conspicuous and to the stranger might have the appearance of being really native. 



Most of this region and the mountain slopes that lie below the forest, where they 

 are not under irrigation or cultivated, have for years been grazed over by cattle. This 

 region is also overrun by foreign weeds, imported by man, and little is left of the native 

 vegetation. Where there is a covering of grasses, these are generally foreign. How- 

 ever, in the most arid districts of the islands, where foreign weeds have failed to 

 establish themselves to any great extent, or at least do not thrive, and on some of the 

 rough lava flows, avoided by the cattle, a considerable number of native shrubs and 

 trees may still be found. In a few places on these dry mountain slopes there yet 

 remain a few choice endemic plants, now mostly extremely rare, such as the red-flowered 

 cotton tree [Gossypium drynarioides) and the shrubby \\o\^X. (Viola helioscopia). Though 

 so greatly denuded, here and there, either singly or in clumps, we meet with various 

 endemic or immigrant species of interest, e.g. Maba, Sanfahtm, Nothocestruni, Gardenia, 

 Nototrichitim, Dodonaea and Erythrina. Pandanus odoratissimits grows scattered or 

 in thickets in many places, and groves of bread-fruit trees occur rarely, as evidence of 

 former cultivation. 



A number of plants of aboriginal introduction belong to this region, but all of 



F. H. I. d 



