ANNALES DE L'INSTITUT OCÉANOGRAPHIQUE i3 



interest is his chart p. 535 showing the spawning-places of three species of lings (Molva) ; 

 these three species spawn from Iceland to the coasts of France, each of them in its own cha- 

 racteristic region as seen by the chart ; it is not easy in few words to characterize these 

 three spawning-regions, which are so different both as regards depth and geographical 

 distribution. I am of opinion, that certain animal communities have a similar distribution 

 in these waters and that in the course of time, to speak summarily of their presence, we 

 shall but name the characteristic animals there, in order to designate the regions spoken 

 of; I really cannot think of anything else as basis for designating these regions, extending 

 like narrow belts along the border of the continent, in which the animals have now made 

 themselves at home. The animal communities would thus become the main thing in {oo- 

 geography like the plant communities in botany. 



The experiments made to set up horizontal divisions for the distribution of the animals 

 along the sea-bottom (in provinces), ought only to comprise the animal communities 

 living in shalloxv water, otherwise too different communities will become mixed; the verti- 

 cal divisions (in zones, belts) have generally only been slightly characterized, but all agree 

 still in separating the abyssal fauna from the littoral. I feel certain, that investigation and 

 charting of the animal communities actually occurring, will comprise everything that is 

 right in both methods. How narrow the limits of such widely distributed animal commu- 

 nities have to be drawn, must be shown by future investigations of their characteristic 

 animals. 



I cannot conclude these remarks on the geographical distribution without mentioning 

 that, as already known, the distribution of the animals and plants in the sea is not exclusiv- 

 ely determined by the surrounding conditions under which they live, but also by con- 

 ditions that are in connection with the development of the earth and with the origin in 

 earlier times of certain species at such places of the earth, where, checked by the exten- 

 sion of land and sea, they have not been able to spread everywhere where they could 

 thrive. It comes however under another division of zoogeography to clear up the latter 

 conditions, but what I specially aim at here, is partly to describe the distribution of the 

 animals within smaller regions where only the factorsof the present timecan be supposed 

 to have any regulating power, partly to try to find the causes of this distribution. One 

 must at least be entitled to suppose, that this restriction of the problem, which permits of 

 a more detailed investigation of the whole of a smaller region, will sooner lead to an 

 understanding of these causes, physical as well as biological, and thereby also obtain 

 theoretical importance. That I hope also by my investigations to obtain some practical 

 results for the benefit of our sea-fisheries, is quite a different matter, which I shall not deal 

 with any further on this occasion. 



