582 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



covered by Chiercliia, wliicli were taken by him in great numbers and 

 in great vertical and horizontal extension, but never higher than 1,000 

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

 the sea bottom (8, p. 85). The deepest part of this zonary fauna forms 

 the haihyhic planMon (or the profound tow-stuil", A<(/ifWe6), i. e., animals 

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

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

 One might also call them ^' abyssal planT<ton,^^ 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 plankton belong many phfpodaria, 

 some inedusie and siphonophores, many deep-sea Crustacea, Tomopteris 

 euchwta, Megalocereus ahyssorum, etc. (15, pp. 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. 



AUTOPELA.GIC, BATHYPELAGIC, AND SPANIPELAGIC PLANKTON. 



If, following the old custom, we limit the term "pelagic hios''^ to those 

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

 if we do not with Chun (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 autoj^elagic, bathypelagic, and sijanipelagic. Autopelagic are 

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

 face (or iu stormy weather at slight depths below it), the "superficial" 

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

 for example, many polycyttaria (most sphiierozoids), many medusae (e. r/., 

 Encoplda'), and many sii^honophores {e. g., ForsJcalicIa'); further, the 

 lobate ctenophores {Eucharis, BoUna), particular species of Sagitta {e. </., 

 hipunctnta)^ and many copepods [e. </., Fontellma, 15, p. 27). 



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

 surface, but also extend down into the dei)ths, and often fill the deei) 

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

 layers. Chun d. signates such bathypelagic animals as "interzonary 

 pelagic animals" (15, p. 45). Here belongs properly the chief mass of 

 the j)lankton; for through the agreeing researches of Murray (5, 6), 

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

 wide experience, it becomes highly probable that the great number of 

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

 swimming at different depths during the other part. Among the 

 bathypelagic animals there are farther to be distinguished: (a) Kycti- 

 2)elagiCj which arise to the surfiice only at night, living in the depths 

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



