82 Journal New York Entomological Society. [voi. iv. 
England to Colorado. According to the classification of the larvee, 'five 
subgroups are common to Europe and North America. Strictly “ re¬ 
presentative ’’ species, true species of replacement, seem to be only alni 
and funeralis, euphorbia and sperata , auricoma and impressci , leporina 
and vulpinci , while, although the moths are very near, the larvae of psi 
(or tridens ) differ rather decidedly from occidentalism so that psi 
tridens and occidentals appear rather as parallel species. The species 
referred to Hybona and Trioena are very numerous in North America, 
the larvae being more or less easily distinguishable, while the moths 
differ chiefly in their relative proportions, the psi pattern being re¬ 
peated in morula , occidentalism has la, furcifera , betulce, grisea, tritonam 
quadrat a, lobe lice , radcliffei. Peculiarly European groups are offered 
by those named by me Apatelam Cuspidia, peculiarly American are 
Megacronycta, Philorgyiam Tricliolonche and Lepitoreuma. 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 Or eta is found 
in Japan and North America. If my suspicion that the California 
spinea and the European menyanthidis 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 Citheroniidse occur only in the East. 
We find in California a true Saturnia and true or typical Hypenam 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 
