cxxii FAUNA HAWAIIENSIS 



supposing it to be a natural immigrant, proves to be such, and is elsewhere known from 

 Florida and Australia. It is Dryoiribus viimeticus of Leconte and Horn, It is inter- 

 esting to find that this beetle has presumably at some distant time reached the small 

 and remote lying island of Midway, and there has given rise to an allied species. It 

 is not known whether typical D. mimeticus occurs there also. Examples from the 

 main islands of the Hawaiian group are in no way distinguishable from American 

 specimens. 



Of the three described species of Pentarthrum, P. obscurum and blackburni are 

 certainly introduced, the latter attacking boxes of foreign wood in Honolulu, and the 

 former is, I believe, also known from Fiji. It attacks trees of foreign origin. Another 

 species of Pentartkrum has recently been imported and lives in the stem of sugar cane. 

 P. prolixuni on the other hand is truly endemic, found only in the mountain forests, and 

 confined to the native tree-ferns. It exhibits considerable variability. Orothreptes 

 callttkrix is widely distributed in the islands, and the genus, if not the species, will no 

 doubt be found elsewhere. It is attached to the naturally present, but not endemic 

 tree, Pisonia umbellifera. The minute weevil, Deiiiocossonus nesioies, is found on various 

 kinds of dead wood, Metrosideriis, Alyxia etc. It is confined to the native forests, 

 from 1500 ft. to 4000 ft, and shows considerable variability. The natural immigrant 

 in driftwood, described by me under the name oi Haloxenns immigrans (Vol. 11, p. 148), 

 belongs to the genus Macrancylus, originally described from Florida. Pseiidolus 

 longiilus, which we have found in consignments of plants from Fiji, is no doubt an 

 imported species. P. hospcs, of later introduction, and first found in the boards of the 

 floor of a room in Honolulu, is now far commoner in the mountains round the city than 

 P. longuius. Where the latter was once common one now finds only P. hospes, as if 

 the latter had in some way dispossessed the other. Phlaeophagosoma tenuis is also an 

 importation, which in recent years we have found amongst Fijian plants, when inspecting 

 these on their arrival at the wharf. The genus Nesotocus, with four species, is a very 

 remarkable endemic form, included by Champion in a small group of Central American 

 genera, distinct from, but allied to the Cossonini. Sometimes these insects are not 

 rare beneath bark or in crevices of the limbs or trunk of Cheirodendron. Whereas in 

 drier districts, e.g. at Kilauea, Hawaii, the beetles remain concealed and at rest during 

 the day, in very wet and dense forests, like those of some parts of Puna and the 

 Kohala mountains, they are active by day, running rapidly over the tree trunks like 

 many Longicorns. Dead branches of Cheirodendron are often riddled by the borings 

 of these species. Individuals vary greatly in size, and, in accordance with this, the 

 structure is much modified in the small examples, the form of the rostrum, antennal 

 joints etc. becoming affected. N. kaiiaiensis is remarkable in having the antennae of 

 the ^ inserted in a different position on the rostrum from that of the others, though 

 otherwise excessively closely allied. Dysomma sylvicola, only once found amongst dead 

 leaves, is of uncertain affinity. 



