.Mil 



As regards llic I'iiciUc-rdasI and (Joloradiaii species, wliich are similar 

 to those inlialMtiiiir the plateaus of the Ural and Altai Mountains, such as 

 the two species of Litliostcgc, Euasjiilafes, and Caulostoma, each of these 

 have representatives which do not occur in Northeastern America nor in 

 Western Europe, but are to be found in Central, Southern, and Eastern 

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

 Eastern Asia, /. c , China or Japan, so tar as yet known. Now, in order to 

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

 suppose tiiat the nearly identical meteorological features of the plateau of 

 Western America and of Asia tiivored tlieir 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 'i'ertiary 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 liuina, 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. Jiiger seems in jiart plausible, He considers, according to 

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

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

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

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

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

 view for Diurnal Lepido])tera. See an abstract of his views in the Bulletin de 

 la Societe entomologique de Belgique, May, 1S74. The original is in Wiirtem- 

 bergcr naturwissenschaftliche Jahresln.'ften, 1873. We have not met with 

 any a])j)licalion, however, of Heer's discoveries and speculations to zoo- 

 geography by European entomologists 



