98 NATURAL SCIENCE. Feb., 



the Gulf Stream and the Azores, whereas the Tomopteridae 

 are abundant there. He mentions an interesting form, which 

 appears to be cosmopoHtan, since it has been found in the 

 China Sea as well ; he says that several species also occur in the 

 whole southern region ; but for other forms he gives special districts 

 of distribution. 



Finally, passing from these groups of animals, we may look 

 forward with interest to the faunistic results that will be obtained in 

 other groups. Some preliminary communications of morphological 

 interest have also appeared (on the pelagic Anthozoa, by Van 

 Beneden, and on Gastropods, by Simroth), and whatever the results 

 may be regarding the uniform distribution of the Plankton in the 

 open sea, though till now they agree very well with the views 

 of the originator of the expedition, we may be sure that our know- 

 ledge of the faunistic distribution and of morphological facts will 

 undergo a remarkable extension by this expedition. 



I will not conclude this short sketch without drawing attention to 

 the practical side of such an expedition, and its value for fishery 

 questions in general. Though it may not appear so at first sight, 

 yet, however any group of the animal kingdom may be related to 

 the other groups, and however far apart some families, classes, or 

 types may stand in the morphological system, they are nevertheless 

 in direct physiological connection. The fishery commissioners' task 

 must be not only to observe the fishes in their occurrence and their 

 wanderings, and to study their enemies and their food, but also 

 to take into consideration every pelagic animal, and to calculate 

 the complicated mutual relations existing between the single 

 groups. 



Thus I can affirm that even the Medusae have an importance 

 for the fishery questions ; not as enemies of the fishes nor as their 

 food, but as competitors. It is well known that small Crustaceans, 

 chiefly Copepods, form the food of most fishes, and the oceanic 

 Medusae, which are beasts of prey, feed on the same material. These 

 Medusae are very voracious (one can often find their stomachs filled 

 to bursting with Copepods) and are very bold in their movements ; 

 they are well provided for the struggle for life in the open ocean, and 

 since they occur in enormous quantities, they are certainly of some 

 importance from the practical point of view as well. 



If we make a little step forwards in the knowledge of the com- 

 plicated relations in which the inhabitants of the ocean stand to one 

 another, the beast of prey and the animal it feeds on, as well as the 

 plants which form the " primaeval food "(Urnahrung) ; in other words, 

 if we come to some understanding of the " production and the meta- 

 bolism of the ocean," then a chief object of the expedition will have 

 been attained." 



1 Some of the first publications of Hensen's Expedition, namely, the descrip- 

 tion of the journey, cS;c., have now begun to appear. 



