THE CANADIAN ENTOMOLOGIST. 125 



the two European species of Bombycia, or and ocularis, we have two 

 from the west coast, iniprovisa Hy. Ed., and semicircular is Gr. But 

 the other European structural types seem to be wanting with us ; Lcptina 

 seems to be quite distinct from these, and an American outgrowth. The 

 species described by Walker from the east, under Cyinatophora, I have 

 partly examined, and have corrected his generic determination, so that it 

 seems unlikely that we have any eastern representative of the European 

 genera. It would seem to be a proof that the west coast fauna more 

 nearly coincides structurally with the PLuropean, that the typical European 

 genus of this sub-family, Bombycia ( Cymatophora), occurs there, and not 

 in the east of North America. There seems to be, finally, some doubt as 

 to what the west coast species oi Habrosyne really is ; whether our eastern 

 scripta, which is rather unlikely, or a form identical with the European, 

 which Mr. Hy. Edwards has suggested. While the species of Pscudo- 

 thyatira seems to extend nearly, if not quite, across the Continent, our 

 eastern T. pudens Guen. appears to be replaced on the west coast by T. 

 lorata Grote. But I have seen no record of this species from California. 



We may believe that the peculiar resemblance of the Californian and 

 west coast fauna to that of Europe, has arisen partly in the fact that the 

 preglacial fauna forced downwards during the Ice Age, has been on the 

 west confined to a comparatively narrow strip between the Rocky 

 Mountains and the Pacific Ocean, and that it has been exposed to lesser 

 variation from migration. The temperature and food-plants necessary to 

 many species are contained in narrower belts, with probably more abrupt 

 confines, precluding the range of the species. Thus the original form may 

 have been longer preserved. 



I may conclude that this sub-family must be regarded as belonging to 

 the Northern Hemisphere, and its representation in the New and Old 

 World, as derived from a former circumpolar fauna. While certain generic 

 forms found in Europe (at least two in number : the hairy-eyed Asphalia^ 

 and the naked-eyed genus of which duplaris is the type), do not apparently 

 occur in America, we have, as an offset, the species of Lcptina. We 

 have also, in the more aberrant group of the sub-family, the pecuhar genus 

 Pseudothyatira, with its one species appearing in two forms, cyniato- 

 phoroides and expultrix. On the whole, then, the representation of the 

 Thyatiriiue, though probably without coincident species, is quite nearly 

 equal in the New and Old World. For, if we have a representative 



