596 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ainoiifi" tlie Acrufipedota. Some Mediisw liave ])Jirtly or entirely given 

 uj) the .swiiiiDiiiig mode of life, as Folydonia, Cephca, and other lihiz- 

 ostoina, which lie with the back towards the sea bottom, the niaiiy- 

 nioutlied bimch of tentacles directed upwards. The LucernarUkv have 

 completely passed over to the benthos. Mawy ^[eduH(c are spanii)elagic, 

 rise to the surface only during a few months (for the purpose of reproduc- 

 tion?), and pass the greater part of the year in the dei)ths; thus in the 

 Mediterranean the beautiful (Jotylorrhiza tuberculata, Charybdea marsu- 

 2)ialis, Tima flavilahrls, and OJhidiaH mnUcrl. These bathybic forms are 

 sometimes brought up in great numbers with the bottom net (19, ji. Vl'l). 

 Many cling with their tentacles to Algce and other objects (20, p. 341). 



The imnu'use swarms in which the Medusw sometimes appear, millions 

 crowded thickly together, are known to all seafaring naturalists. 

 Thus in Arctic waters, Godoniiim jjrinceps, Hippocrene super eiliaris; in 

 the North Sea, Tiara pileata, Aglantha digitalis; in the Mediterranean, 

 Liriantha mucronata, Hhopaloncma velatxiii; in the tropics, Cytais 

 nigritina; in the Antarctic Ocean, Hippocrene mocloviana and others. 

 Hensen (9, p. G5) in the North Sea found a swarm of Aglant/ia, the 

 number of which he estinuited at twenty-three and one-half billions. 

 The extent of the multitude was so great that "the thought of approxi- 

 mately estimating the animals in this swarm must be given i;p." In 

 such cases the whole sea for a few days, or even weeks, seems every- 

 where t'ullof 2Iednsa'; and then again weeks, or even months, may pass 

 without linding an individual. The uncertainty of appearance, the 

 " capriciousness of these brilliant beauties," in other words the depend- 

 ence upon many different, and for the most part unknown causes, is in 

 this interesting animal group remarkably impressed u])on us. I will, 

 therefore, in another place, refer to it on the ground of my own experience. 



iSiphonophorcs. — What I have said above concerning the unequal dis- 

 tribution of the medusic api)lies also to their wonderful descendants, 

 the purely oceanic class of the siphonophores. This highly interest- 

 ing class was, up to a few years ago, also regarded as purely pelagic; 

 but of these, too, it is now known that they are in great part bathy- 

 pelagic, in i)art also zonary and bathybic. The new and very peculiar 

 group of the Auronecta' {Stcphalida' and Rhodalida'), taken by the Chal- 

 lenger at a depth of 200 to OUO fathoms, is described in my "•Report of 

 the Siphonophores of H. M. S. (Jliallenger^^ (188S, p. 29(5). The Hathy- 

 physa taken by Studer, and some qH the Ehizophysida' {Aurophysa, Lino- 

 physa) captured by the (hizellc, were taken at a. depth of 000 to J, 000 

 fathoms (1. c). But that such deep-sea siphonophores (pro])ably mostly 

 Rhizophysidw) inhabited the ocean in great masses was first shown by 

 Chierchia (8, p. 84-8G). Previously, in numerous soundings which the 

 Vcttor risani had made in the Atlantic and Pacitic oceans, the line of 

 the deep-sea lead when drawn up was found to be wound around with 

 the torn-oflf stinging tentacles of great siphonophores. By means of 



