.V.I I 



As regards the L J acific-coas1 and Coloradian species, which are similar 

 in those inhabiting the plateaus of the Ural and Altai Mountains, such as 

 the two species of Lithostege, Euaspilates, and Caulostoma, each of these 

 have representatives which do not occur in Northeastern America nor in 

 Western Europe, hut arc to be found in Central, Southern, and Eastern 

 Europe and Asia Minor, Turkey, and Western Asia, lint not in India or 

 Eastern Asia, i, e., China or Japan, so far as yet known. Now, in order to 

 account for this identity of generic types in regions so remote, we are led to 

 suppose that the nearly identical meteorological features of the plateau of 

 Western America and of Asia favored their preservation, their ancestors 

 having migrated from an arctic continent to the northward, while forms, 

 either identical or allied, existing in intermediate areas have become extinct. 

 We may imagine that much the same continuity of life existed, in Mesozoic 

 and Tertiary times, in the ancestors of the inhabitants of the north tem- 

 perate zone as now exists in the frigid zone, and composing the circum- 

 polar fauna, and that, in fact, this north temperate fauna of the globe was, 

 in Mesozoic and Tertiary times, the then circumpolar fauna. 



As regards the theory as to the origin of the European insect-fauna, 

 that of Dr. Jager seems in part plausible. He considers, according to 

 Hoffmann, that it is composed of three elements: 1. A Glacial fauna, which 

 inhabited Europe during the Glacial period ; 2. Species which during the 

 Grlacial epoch retired into the Mediterranean region, and which since then 

 have -recrossed the Alps; 3. The larger compose a group which originally 

 emigrated from the North of Asia (Siberian fauna). Hoffmann adopts this 

 view for Diurnal Lepidoptera. See-an abstract of his views in the Bulletin de 

 la Societe" entomologique de Belgique, May, 1874. The original is in Wiirtem- 

 berger naturwissenschaftliche Jahresheften, 187,">. We have not met with 

 any application, however, of Heer's discoveries and speculations to zoo- 

 geography by European entomologists 



