610 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



3. Mo)iotonic Protozoivriankton. — Among the unicellular Protozoa, 

 three diflerent groups, the NoctUuca^ Glohigeri)ia, and Radiolaria, ap- 

 pear ])('higically iu such quantities that they form the greater ])art of 

 the volume of the i)hiiiktoii. The niotiotonic noctiluca-plaitlton is neritie, 

 and is composed almost exclusively of milliards of the common Nocti- 

 Inca miliaris. It forms the reddish-yellow covering of slime upon the 

 surface of the coast seas, and in tin; ocean always points out the litto- 

 ral currents. On the other hand, the widely distributed monotonic glo- 

 higcrina-planliton is purdy oceanic, the point of origin of the glohigcrina 

 ooze of the deep sea. In diflerent regions of the ocean it is composed 

 of different genera of the above-mentioned pelagic thalamophores. 

 Much more manifold in tlia monotonic ra(liolaria-2)lanl'ton, iilso oceanic. 

 Of these, one can distinguish the three following modifications:* 



(1) Polyci/ttann-PlanMon, sometimes composed only of Collozoiun, 

 sometimes of Sphccrozoum, sometimes of Gollosplucra, most often of a 

 mixture of these three forms; in the warmer seas, partly pelagic, partly 

 zonary; very abundant. 



(2) AcaHtharia-Plankton, commonly formed of milliards of a single or 

 of a few species of Acanthometron (in the colder seas, e. g., on the east 

 and west coast of South America, south of 40° S. lat. ; also north of 

 SQC" N. lat. on the coast of Shetland, Faroe-Orkney, and Norway) ; partly 

 autopelagic, partly bathypelagic. 



(3) Phwodaria-Planlcton, zonary and bathybic, mostly composed of the 

 larger species of AuJosphwridw and Sagosphwrida', Calodendridw and 

 Goelographidce [e. g., Goeloplegina murrayanum from the Faroe-Orkney 

 Channel, 4, p. 1757). 



4. Monotonic Cnidaria-PlanMon. — In the group of nettle animals 

 there are numerous forms of meduste, siphonophores, and ctenophores, 

 which appear in immense schools. The monotone medusa-plankton is 

 chietiy neritie, composed of very diflerent local forms on the diflerent 

 coasts. Of the larger Acraspedota, in the warmer seas Rhizostoma [Pil- 

 emidxe, Cramhessida') particularly occur; in the colder, Semostoma 

 {Anrelidic, Cyanida'), which in schools fill tlie littoral bays and cur- 

 rents. Of the oceanic Scyphomcdus'w, Pelagia seems to form similar 

 schools. Among the Craspedota, nu)notonic medusa-plankton is espe- 

 cially formed of neritie Cordonida\ Ma rgel idee, niid PJucopida'^ of oceamc 

 uJUqnoridw, Liriopidce, and TracJtyncmida'. Monotonic siphonophora- 

 planlcton occurs only in the warmer seas, although Diphyidea are found 

 abundantly in all parts of the ocean. The remarkable blue troops of 

 the pelagic Physalidw, Porpididw, and VeleUido) have for a long time 



*Ra(li<)l:iriiiT\-pl;mktoTi is contained in 13 proparatioiis of the Radiolaria collection, 

 which I liaA-e collected (1890) and which can be boutjht throii,ij;h the lamulns Franz 

 Tohle at Jona; 8 of thost^ i)ro|»arations contain p(dycyttaria-plankton, 2 acantharia- 

 ])lankton, an<l 3 pha'dodaria-plaiikton. Tliis collection (of 34 microscopical prepa- 

 rations) embraces in addition 17prc])arationH of the radiolarian-ooze of the deep eea, 

 and 4 i)reparations of deep sea liorny-siiongeH, whoso pseudo-skeleton is composed 

 of radiolariau slime. (Challenger Rei)ort, part lxxxii.) 



