dispersed by ice-floes and drift-wood, i. 14
means of dispersal of aquatic, i. 15
of most importance in determining zoological regions, i. 57
classification of, i. 85
birthplace and migrations of some families of, i. 142, 153
cosmopolitan groups of, i. 176
of the Palæarctic region, i. 181
of the European sub-region, i. 192
of the Mediterranean sub-region, i. 202
of the Siberian sub-region, i. 217