COLEOPTERA 



119 



known, but the great majority of the species belong to the widely distributed genus 

 AcalL's. 



or the Cossonini, Oodemas, Heteramphus, Anotheoriis, Nesotocus, Dysomnia, 

 Deinocasoims, and Orothreptes are all genera peculiar to the islands, and it is probable 

 that some members of the genus Dryoplithoriis will at some time be separated as 

 distinct, while the rest will remain in that or be placed in very closely allied genera. 

 The indigenous Pentarthriim is a remarkable insect, very different to the two foreign 

 exponent > of the genus, but said to be allied to New Zealand forms (Sharp, Tr. ent. 

 Soc. Lond. 1878, p. 25). Thus nine of the 13 genera of indigenous Curculionidae are 

 peculiar to the islands, while Rhyncogonus with its numerous species probably originated 

 in the Pacific region and will be found to be widely distributed therein. With regard 

 to Acalles Sharp has remarked (Tr. Dublin Soc. 1885, p. 269) that it "is one of the 

 most frequent components of insular faunae, being very richly represented in New 

 Zealand, Polynesia, and the Atlantic islands." 



Distribution of genera and species in the islands. Of the six genera which 

 contain each but a single species, the two Cryptorhynchids, H ypei'omorpha and Chae- 

 nostermmi, have both been found on Oahu alone, and the Cossonideous genera Dysomma 

 and Orothreptes are peculiar, the first-named to Kauai, the latter to Hawaii, whereas 

 Deinocossonus is probably to be found on all, since it has been taken on Kauai and 

 Hawaii at either end of the group as well as on the intermediate island of Oahu, and 

 the indigenous Pentarthruvi is likewise ubiquitous. It must however be remembered 

 that all the above-named insects, excluding the Pentarthriun, are excessively rare and 

 difficult to procure, so that more extended observations might show that those apparently 

 peculiar to one island also occur on some of the others. Nesotocus has been found 

 alive on Kauai, Maui and Hawaii, and fragments also on Molokai, so that it is no 

 doubt of general distribution, but Anotheorus is wanting on Hawaii, its range being 

 from Kauai to Maui. The distribution of Heteraniphus is similar to that of 

 Anotheorus, except that whereas we failed to collect the latter on Molokai, so Heter- 

 aniphus was not found on Lanai, but both are found on the neighbouring island of 

 Maui. The extensive genera Oodemas and DryophtJiorus are ubiquitous over the 

 group, as also is Acalles, but Rhyncogonus apparently becomes scarcer on the windward 

 islands, and is altogether absent from Hawaii. 



The species of the genus Rhyncogonus, e.xcepting only R. sordidus, which was 

 iound alive on Lanai and in fragmentary condition on Molokai, are confined each one 

 to a single island, and of the 19 species Kauai has no less than nine, Oahu four, 

 Molokai three, Lanai and Maui two each, whilst Hawaii, as has been remarked, has 

 none. 



Of the 20 species of Acalles the three islands, Kauai, Oahu and Hawaii have each 

 four species, and Maui and Lanai three each, while one species is found throughout the 



