348 C. SKOTTSBERG 



Xt'sotflcus is evidently a relict endemic genus of four closely allied species, and 

 there aj)pears to be nothing like it elsewhere . . . Oodemus with its 58 species ... is 

 the largest genus of the Hawaiian Cossoninae . . . together with its close ally Atiotherus 

 (3 species) endemic, and I know of no genus or group of genera from any region from 

 which is might have come. It is an anomaly. 



Such cases brini^ us back to times long before the formation of the present 

 Hawaiian chain, and similar cases are found also in Juan Fernandez, e.g. the 

 endemic tribe yidviorJuui of .Vl KI\ILL11 s. Other examples are offered by many 

 other insect groups. And, leaving them aside for a moment, is not the endemic 

 Hawaiian bird family Drepanididae another anomaly.^ Whereas Brvan [j^g. 188) 

 finds a Malayan origin most acceptable, GULICK writes (7/^.420): 



The history of Hawaiian land birds must have begun with the arrival of some form 

 of troi)i(al American honey creeper, which became in due time the progenitor of all 18 

 genera and 40 sj)ecies of the Drepanididae. 



Me seems to have forgotten that the islands are claimed to have cHved out of 

 the ocean in late Pliocene and Pleistocene times. 



I lyinoioptcra are plentiful in Hawaii, about 600 native species, among which 

 endemics are numerous, and the ancestors are supposed to have come from the 

 south and southwest Pacific, in exceptional cases from Asia and the Orient. This 

 order is as yet little known in Juan Fernandez, see above p. 315. Wind drift seems 

 to be the only possible mode of transport unless infected larvae of butterflies etc. 

 arrived with drift-wood, which does not seem very probable. Ants are easily spread 

 with the traffic. Of the 3 species known in Juan Fernandez only one appears to 

 have arrived without human assistance. 



Among the Heteroptera in Hawaii, over 200 species and 80 % endemic, ZlM- 

 MKRMAN pays special attention to the genus Xysius, which has its greatest known 

 diversity in those islands. All are endemic and include the most divergent of all 

 Xysius species. The ancestors are supposed to have come from the south and 

 west Pacific. The genus is, according to UsiNGER (2'/j) common in the Australian 

 and Oriental regions, extending through Melanesia to Fiji anci Samoa without a 

 single re[)resentative east of this line, but important in the Hawaiian chain; the 

 author seems to have overlooked its occurrence in Juan Fernandez. Xysius is 

 su()posed to have reached Hawaii by a circuitous route over open water and the 

 Leeward Hawaiian islands. This route is indicated by a submarine ridge of con- 

 siderable depth and may once have been interrupted by island peaks such as 

 Wake Island; thence it is followed to the Marianas and Caroline Islands and even- 

 tually to the rich Papuan and Australian regions, l^ut in other cases it is less 

 eas)- to construct a suitable route: "The presence of twenty very unique genera 

 in Hawaii and their absence from old, high islands along the very route they are 

 said to have traveled is inexi)lical)le by present theories" (I.e. 315). Why not 

 presume that all related genera have died out.-, which is the easiest explanation. 



Xysius is a widespread genus, well developed also in New Zealand, and the 

 single Juan I^'ernandez species is claimed to be related to another from New Zea- 

 land. We know numerous examples of the same kind in other animal groups and 

 particularly among the plants we have called Antarcto-tertiary. 



