Our knowledge concerning the periodical movements in animals called migrations is chiefly based on observations on birds. By and by, however, a number of facts concerning migration in other animal groups have been assembled and it seems worth while to compare them with those known for birds. There is the more reason to do so here, because the victim of this jubilee is interested in birds and fishes alike. Though I shall not restrict myself to these two groups they will take more place than the rest. In the following I shall deal with North to South and South to North migrations chiefly. In the hope to succeed and make my ideas comprehensible to those who are not specially acquainted with this particular field I shall begin with a very short description of the migration of some animals in the sea, which may be used as a starting point for the comparison which follows next. These animals are the cuttlefish ( Sepia officinalis L.), two species of fish: the anchovy ( Stolephorus encrasicholus (L.)) and the tunny ( Thunnus thynnus (L.)) and, finally, a mammal: the humpback (Megaptera novaeangliae (Borowski), one of the whales.