J. W. Fewltes — Deep-Sea Medusae. Ill 



life, between those living on the bottom 'or close to it and the 

 surface fauna." 



This statement from such a high authority in the study of 

 marine zoology would seem to effectually crush any murmur 

 of belief in intermediate zones in the distribution of oceanic 

 forms of life. While I have the highest respect for this view, 

 I cannot help entertaining an opinion that more observations 

 are necessary before we can accept the proposition that there 

 are not characteristic belts of pelagic animals at different 

 depths. 



With the question whether the recorded depths at which 

 the Medusae which we shall consider are found, are accurate or 

 not, we cannot deal. Indeed, at this stage of this kind of 

 deep-sea exploration, an examination of these methods would 

 be foreign to the purposes of this paper. We take the data as 

 given by the collector and at present leave the improvement of 

 the collecting apparatus to others. 



Can we not approach this subject from another side ? Are 

 there any characteristics in the Medusae themselves which show 

 that they are preeminently fitted to live at the depths or ap- 

 proximate depths from which they are reported ? Has their 

 habitat left any traces in the modification of their anatomy ? 

 Has the uniformity of conditions in their habitat led to a cor- 

 responding simplicity in their structure and are they nearer the 

 ancestral forms than others with a more varied environment ? 

 An account of the singular structure of one or two typical 

 genera may help us to answer this question or at all events 

 present certain facts which bear upon it. Let us therefore for 

 illustration consider one or two representatives of the Acras- 

 peda and Siphonophora discovered by the Albatross in the 

 depths of the Grulf Stream. 



Everyone familiar with the anatomical structure of the 

 Siphonophores will recognize how difficult it is to find in those 

 genera like Rhizophysa anything to point to an adaptation to 

 a deep-sea life. The Albatross has discovered new Physo- 

 phores closely allied to Phisophysa, one of which, Petrophysa, 

 reaches the enormous size of twenty feet in length in alcohol. 

 The float of this animal is larger than that of any true Siphon- 

 ophore except Physalia. The large size of the float in these 

 Physophores would seem an effective argument against their 

 adaptation to a life in deep water, especially as their nearest 

 ally, Physalia, is preeminently a surface form. 



It is extremely difficult to gather from the structure of the 

 known Siphonophora ascribed to the deep-sea anything to indi- 

 cate an adaptation to such a life. The group can afford little 

 satisfaction in our answer to the question of whether there is a 

 nomadic deep-sea life or not. 



