liv FAUNA HAWAIIENSIS 



be considered sufficient for the production of the long series of allied species that they 

 contain, without the supposition of several or numerous immigrant species. In compact, 

 smaller groups like the longicorn beetles of the tribe Plagithmysini, the probability of 

 the origin of the Hawaiian series from a single form is, I think, not likely to be 

 disputed by those who have studied the creatures. There are three genera, and the 

 differences between the extreme species is great. Supposing the existing species to 

 have arisen from diverse immigrant species, it would be natural to suppose that one 

 immigrant at least represented each of the three genera. When, however, we look 

 into the differences between these genera, we find that though the bulk of the species 

 are easily enough placed, each in its proper genus, yet some species, forming distinct 

 connecting links between the genera, are still existing. Thus oi Plagithmyszis immundus 

 Dr Sharp remarks : " It is a connecting link between Clytarlus and PlagitJmiysus" 

 while Callithmysus C7'istatus, once referred to Plagithmysus, shows evident relationship 

 to some species of the latter and also to Clytarhis. 



It is when we come to examine the more complex groups of allied genera such as 

 occur in the Carabidae or the Drepanid birds, that there is greater room for diversity of 

 opinion as to the multiple or single origin of the Hawaiian forms, as they exist at 

 present. As to the Drepanididae, their case has already been considered in the part of 

 this work dealing specially with the birds. It is of some importance on account of the 

 fact that these birds may by some botanists, who consider the flora to have largely been 

 established through the agency of these creatures, be considered responsible for the 

 introduction of a not inconsiderable portion of the existing plants. If however, the 

 existing forms have all sprung from a single or dual chance immigration in long past 

 ages, the part that this dominant group of land-birds can have played in the establish- 

 ment of a flora will be necessarily very small, or possibly of no account at all. 



It may be worth while to consider some points in connection with the two 

 important and quite distinct groups of endemic Carabidae, the Anchomenini and 

 Pterostichini. The 17 genera of the former group have been divided by Dr Sharp 

 into two divisions, one with ten, the other containing seven genera. The character 

 separating these divisions is derived from the structure of the tarsi, which in the one 

 case have a peculiar grooved structure, while in the other they are simple. Amongst 

 the genera with grooved tarsi, however, there exist species in which the sculpture is 

 very much reduced or indistinct, and in the genus Colpocaccus, some of the species 

 have the grooves much more developed than others. In Metromenus, one of the species 

 {M. politus) not only has the grooving of the tarsi very obscure, although it belongs 

 to a genus in which this sculpture is comparatively strongly developed generally, but 

 in other respects it bears considerable resemblance to members of the division with 

 unsculptured tarsi. The characters on which the individual genera are separated in 

 these two divisions of Hawaiian Anchomenini are chiefly (i) the condition of the wings, 

 whether rudimentary or well-developed, (2) the absence or presence of sensory setae on 



