Vol. I] WILLIAMS— BUTTERFLIES AND HAWK-MOTHS 319 



distinct from their progenitors, shows that at least some of the 

 fauna is of considerable antiquity, and that migrations to 

 these islands have not been frequent or often successful. Cli- 

 mate and environment and isolation seem to be responsible for 

 the evolutionary changes. 



The study of the fauna of oceanic islands is an excellent 

 guide for the determination of hardy migratory forms. We 

 find Pyrameis huntera also inhabiting the Hawaiian Islands; 

 likewise the moths, Deilephila lineata, Phlegathontius con- 

 volvuli {cmgulata Fabr.), Agrotis ypsilon, etc. The Hawaiian 

 and Galapagos Islands are separated from each other by a vast 

 expanse of ocean, yet they have some forms in common. 

 There are only seven butterflies and seven hawk-moths known 

 from the Hawaiian Islands, and this fauna is also compara- 

 tively meager in the Azores, Bermudas, Samoan, Friendly 

 Islands, etc. 



The almost ubiquitous Anosia plexippus, which is found on 

 a number of the oceanic islands, does not yet occur in the 

 Galapagos, although a Milkweed (Asclepias angustissima, 

 Andersson), is plentiful on some of the islands, 



Utehesia ornatrix (Arctiidae), Erebus odora (whose food- 

 plant, a large leguminous tree has probably been introduced), 

 Agrotis ypsilon, Meliopotis nigrescens and sinualis, and spe- 

 cies of Prodenia (Noctuidse), are among the Galapagos 

 insects which are familiar to many collectors in the United 

 States and elsewhere. 



Notwithstanding the fact that the flora and fauna of the 

 Galapagos are fairly well known, there still remains an 

 immense field for further investigation there, and the only 

 manner in which a satisfying knowledge of the natural history 

 of these interesting islands could be obtained, would be by 

 residing in the Archipelago for several years, and studying 

 the fauna in all its relations in a most thorough and systematic 

 manner. This little paper does not claim therefore to be much 

 more than an imperfect study of the subject; yet it is based, 

 however, on rather ample field notes and observations by the 

 writer himself. 



