82 Journal New York Entomological Society. [voi. iv. 



England to Colorado. According to the classification of the larvae, five 

 subgroups are common to Europe and North America. Strictly " re- 

 presentative '' species, true species of replacement, seem to be only alni 

 and funeralis, eiiphorhicE and sperata, auriconia and impressa, leporina 

 and vulpina, while, although the moths are very near, the larvae of psi 

 (or tridens) differ rather decidedly from occidentalis, so that psi 

 tridens and occidentalis appear rather as parallel species. The species 

 referred to Hybona and Tricena are very numerous in North America, 

 the larvje being more or less easily distinguishable, while the moths 

 differ chiefly in their relative proportions, the psi pattern being re- 

 peated in morula, occidentalis, iiasia, fiircifera, betiihx, grisea, tritona, 

 qnadrata, lobelice, radcliffei. Peculiarly European groups are offered 

 by those named by me Apatela, Cuspidia, peculiarly xAmerican are 

 Megacronycta, Pliilorgyia, Tricholonche and Lepitoreiima. Taking all 

 the groups in the synopsis as distinct, we have eight American, three 

 European and five common to both faunae, from larval characters alone. 

 Although in North America the genus Apatela offers peculiar out- 

 growths, so to speak, its affinity with the European is decided. We 

 may therefore regard it as one of the survivors of a former holoarctic or 

 circumpolar fauna, which would have been forced southwards, both in 

 America and Asia, by the advent of the Glacial epoch. Traces of this 

 European affinity are found in the moths of Japan, and has then the 

 same origin. To the same shifting of the faunal extension, the sunder- 

 ing of species once occupying an extended territory, through climato- 

 logical changes, we must ascribe the fact that the genus Oreta is found 

 in Japan and North America. If my suspicion that the California 

 spinea and the European meiiyauthidis are related is verified, it would 

 be another link in the chain of facts which go to show that the Rocky 

 Mountains have proven a barrier to the extension of certain types to 

 the eastward. Conversely the Citheroniidte occur only in the East. 

 We find in California a true Sati/rnia and true or typical Hypena, to- 

 gether with Arctian and other types having a strong European facies. 

 It seems natural to suppose that these have taken a west coast direction 

 in the glacial movement to the south, and there now maintain them- 

 selves. The occurrence in Maine and Canada, north of the Great 

 Lakes, of species of Pyrausta and Agrotis, which we know from British 

 Columbia or northern parts of California, may be explained not only 

 on the general principle of a southward migration over the whole terri- 

 tory, but possibly by the fact that inter-communication between the 

 West and East meets to the northward in certain places less difficult 



