r>82 KKPOUT OF COMMISSIONER OF FISH AND FISHERIES. 



covered by Chiercliia, whicli were taken by liim in j^reat iiuinbers and 

 in great vertical and liorizontal exlciision, bnt nevH'r liiglicr tlian 1,000 

 meters below the surface and never deeper than 1,000 meters above 

 the sea bottom (8, p. So). The deepest part of this zonary fauna forms 

 the haihyhie lAanlion (or the profound tow-stuff, Aiiftrieh), i. c, animals 

 of the deep sea, which only hover over the bottom but never touch it, 

 whether they stand in definite relation to the abyssal benthos or not. 

 One might also call them '■'■abyssal plmildon^''^ if it were not more prac- 

 ticable to limit the term " abyssal" to the (vagrant and sessile) benthos 

 of the deep sea. To the bathybic i^lankton belong nurny i)li{eodaria, 

 some medusa' and siphonophr)res, many deep-sea Crustacea, Tomopteris 

 eucha'ta, Meyaloverens ahyssorum, etc. (15, i^p. 55-57). 



In each of these vertical parts of the plankton, distinctions may be 

 made which apply to the horizontal distribution. We may also dis- 

 tinguish oceanic and neritic forms in the pelagic fauna as in the zonary 

 and bathybic fauna. 



AUTOPELAGIC, BATHYPELAGIC, AND SPANIPELAGIC PLANKTON. 



If, following the old custom, we limit the term "pelagic ft/os" to those 

 organisms wiiich, at some time, swim or float at the surface of the sea — 

 if Ave do not with Chnn (15, p. 45) extend this term to the zonary and 

 bathybic animals — it still is necessary to further distinguish by differ- 

 ent terms those forms of life which constantly, temporarily, or only 

 exceptionally live at the surface of the sea. I suggest for these the 

 terms auto})elagic, bathypelagic, and spanipelagic. Autopelagic are 

 those animals and plants which are constantly found only at the sur- 

 face (or in stormy weather at slight depths below it), the "suiierficial" 

 of Chun (15, pp. 45, 60). To this "constant superficial fauna" belong, 

 for example, many polycyttaria (most spha?rozoids),many medusre {e.g., 

 Eucopifla'), and many siphonophores {e. r/., For si- a lid a'); further, the 

 lobate ctenophores {Eueharis, Bolina), particular species oi Sagitta [e. g., 

 bipunetata), and many copepods {e. .</., PonieUina, 15, p. 27).- 



I call bathypelagic all those organisms which occur not merely at the 

 surface, but also extend down into the (lei)ths, and often fill the deep 

 layers of the ocean in not less astonishing multitudes than the surface 

 layers, Chun designates such bathypelagic animals as "interzonary 

 pelagic animals" (15, ]>. 45). Here bcilongs i)roperly the chief mass of 

 the i)lankton; for through the agreeing researches of Murray (5, G), 

 Moseley (7), Chierchia (8), and Chun (15, 16), as well as from my own 

 wide experience, it becomes highly i)robable that the great number of 

 pelagic animals and phmts only pass a part of their lives at the surface; 

 swimming at different depths during the other part. Among the 

 bathypelagic animals thcii^ are fartlier to \h\ <listinguished: {a) Xycii- 

 pelagic, which arise to tlu", surface only at niglit, living in the dcjjths 

 during the day; very many medusiTj, siphonophores, pyrosoma, most 



