57 



I'ller i .lull Maaned, at man Ims us ialmindcliglied 

 tiiiiler (leiinc Furni f'nldt lulvikli-t. .leg liar paa 

 denne Tid ol)sprveret den i store ^Fæiigder i Sniaa- 

 tjern paa Dovres Hoideplateau, Øst at Jerkin. S(]in 

 Tilfældet svnes at være med de fleste Phylli>|i(i(ler, 

 naar den temmelig tidligt, og længe for den er fnldt 

 udvoxet, Kjonsmodenlied. De storste Individer tin- 

 der man derfor ialmindeliglied længere nd paa Ho- 

 sten, medens Størrelsen forst jnia Sommeren er be- 

 tydelig ringere. Ofte er der ogsaa paa samme Tid 

 adskillig Forskjel i Størrelsen i forskjellige nær- 

 liggende Tjern. I samme Tjern finder man derimod 

 i liegelen alle Individer omtrent ens iidviklede og 

 af ens Farve. 



Det er et meget livligt Dyr. som er i uafbrudt 

 Bevægelse, oftest mere eller mindre nær Overtladen 

 af Våndet. Bevægelsen tilveiebringes liovedsageligt 

 ved Branchialfoddernes Svingninger, der foregaar 

 paa en meget regelmæssig og elegant Maade, idet 

 de ikke sker noiagtig samtidigt for alle Fodders 

 Vedkommende men siiccessivt, hvad der giver Ind- 

 ti'ykket af en eindommelig Undulation i Bevægelsen. 

 Den herved frembragte Lokomotion er en ganske 

 jevn i horizontal Retning, hvorunder Dyret altid 

 vender Ryggen nedad. Dog kan det foretage mange 

 forskjellige Volter i Våndet og dreie og sno sig i 

 alle Retninger, Inorxed Halens Bevægelser spiller 

 en væsentlig Rolle. Hanner og Hunner sees ofte i 

 Kojjulation, idet Hannen med sine Gribeantenner 

 fast omslutter Hunnens Genitalsegment fra Ryggen 

 af, og saaledes kan begge Individer svomme om i 

 lange Tider, begge vendende Bugsiden ojiad. Selve 

 Kopulationsakten har jeg ikke faaet oliserveret. 

 Rimeligvis afventer Hannen det Uieblik, da de 

 modne Æg fra Ovarierne træder ind [i Basis af 

 Rugesækken, hvor de, som ovenfor anfort, omgives 

 af sin Skal. 



Dyrets Fode synes bovedsagidigt at beståa af 

 niikr()sko|iiskp Alger og andre PlanttMb'lc, tildels vel 

 ogsaa af Infusorier, der ved Bi'ancliialfodderues Spil 

 hvirvles ind mod i\Iunilen. 



Udbredning. — Nærværende Phyllopode ei- forst 

 beskrevet lia (ironland, hvor den synes at \ært' 

 meget alinindclig, og er senere bleven gjenfundcn 

 ]iaa IliTc andre Steder, saaledes drt arktiske Ame- 

 rika, paa Sjiitsbergeii, Xovaja Semija, Kolahalvoen 

 og i Sibirien. Idethele falder dens I'dbredning, naar 

 undtages (Ifl o\ Tiina'vntc Findested i Norge ])aa 

 Dovres Hoidciilatfau. udidukkende indenfor den ark- 

 tiske Zone, og dens I''orekomst her .synes at stemple 

 den som en a'gte arktisk og circnmpolar Form. 



or July that this form is generally found fully 

 developed here. At that season J have observed 

 it in great numbers in small lakes on the high 

 jilateau of the Dovre Mountains, east of -lerkin. 

 As seems to be the case with most I'hyllojioda. it 

 attains sexual maturity tiderably early, and long 

 before it is fully grown. The largest specimens are 

 therefore generally found later in the autumn, while 

 the size in the beginning of the summer is veiy 

 much smaller. There is also often considerable 

 difference in their size in ditferent lakes, while on 

 tlie other hand, all the animals in one lake are, as 

 a rule, uniformly developed, and uniform in colour. 



It is a very lively animal, and in constant 

 motion, generally more or less near the surface of 

 the water. The movement is chiefly brought about 

 by the vibrations of the branchial legs, which take 

 place in a very regular and graceful manner, not 

 quite simultaneously with all the legs, but succes- 

 sively, thereb3' imjiarting to the movement a peculi- 

 arly iindulatory effect. The motion thus ])roduced 

 is equable and in a horizontal direction, the liack 

 of the animal being always turned downwards. It 

 may, however, make all kinds of sjirings in the 

 water, turning and twisting in every direction, the 

 movements of the tail playing an important part in 

 these evolutions. Males and females are often seen 

 in copulation, the male, with his prehensile antennæ, 

 firmly embracing the female's genital segment from 

 the back, and in this manner lioth animals may 

 swim alioiit for a bnig time with the ventral side 

 uppermost. The act of copulation itself. I have not 

 witnessed. The male prolialily awaits the moment 

 when the mature ova enter from the ovary into the 

 base of the marsujiium, wliere. as ]ir('viously stated, 

 they are enveloped in their shell. 



The food of this animal seems to consist jiriii 

 cijiallydf microscopic algie and portions of other 

 jilants, ])artl\' also of infusoria, which are swept in 

 towards the mtntth by the movement of the bran- 

 chial legs. 



Distribution. — The present Phylhqiod was fir.st 

 described tiom (Treenland. where it seems to be 

 very common, and has since been found in several 

 other places, e. g. arctic America, Sjiitzliergen. 

 Novaia Zcmlia, the Kola Peninsula and in Siiieria 

 Altogether its distriliutioii, with the excejition of 

 the above-named place in Norway, on the high pla- 

 teau of the I>ovre Mountains, is exidusively within 

 the arctic zone, and its occurrence there seems to 

 stamp it as a true arctic and circuiii]iolar form. 



li. 0. Savs 



Fauna .Vorro/Za*. 



