113 



o-anske stopper op. Det sker kun, naar Dyret plud- 

 selig foruroliges, i hvilket Tilfælde alle Dele af 

 Ijegemet Imrtigt trækkes ind i Skallen, livorpaa 

 denne hermetisk lukker sig og Dyret synker til- 

 l)unds. Meget snart aabuer imidlertid Valvlerne 

 sig igjen, den forreste Del af Hovedet tilligemed 

 Aarerne strækker sig forsigtigt frem fortil, og Halen 

 bagtil, livorpaa igjen Branehialfodderne begynder 

 sine rhythmiske svingende Bevægelser. 



Dyret synes hovedsageligt at nære sig af op- 

 smnldrede Plantedele, encellede Alger, niaaske ogsaa 

 Infusorier. Disse Dele bliver ved Branchialfoddernes 

 Bevægelser hvirvlet ind i Skallen og passerer der- 

 etter bagfra fortil mellem Fodderne imod Munden. 

 Ivindbakkerne sees at være i stadig Aktivitet med 

 at bearbeide den af Munden optagne Næring, som 

 derefter ved Hjælp af de talrige fra Overlæben til 

 Spiserøret gaaende Musklers Virkning bliver svælgt 

 og indfort i Tarmens forreste Del. Her undergaar 

 Foden en forelobig Oplosningsproces ved det intenst 

 gule Secret, der udsondres af Leveren. Fordoielsen 

 synes idethele at gaa meget hurtigt for sig, idet 

 Tarmens Contenta hurtigt forandrer sin Farve, etter- 

 som de passerer bagtil, fra lyst gult eller orange 

 til et meget morkt brunt eller næsten sort. Med 

 visse Mellemrum bliver Excrementerne ved Ende- 

 tarmens Contractioner iidstodte, ofte'i temmelig lange 

 sanimenhængende Masser. I Liglied med hvad Til- 

 fældet er hos Branehipodiderne, observeres ofte i 

 Tarmrorets Vægge energiske peristaltiske Bevæ- 

 gelser. 



Som ovenfor anfort, har alle liidtil observerede 

 Individer af denne Form vist sig, ifølge sit hele 

 Udseende. at være Hunner, og alle Exemplarer bli- 

 ver ogsaa uden Undtagelse, naar de har opnaaet en 

 vis Grad af Udvikling, for.sjmede med de characteri- 

 stiske Ægpaketter under Skallens dorsale Del. Da 

 jeg har observeret denne Form gjennem en Eække 

 af Aar til forskjellige Tider af Sommeren, og tillige 

 gjentagne Gange har opdrættet den i mine Aqvarier 

 og havt den gaaende her maanedsvis, tror jeg med 

 fuld Sikkerhed at kunne constatere, at Hanner over- 

 hovedet ikke existerer, og at altsaa nærværende 

 Phyllopodes Forplantning er exclusiv parthenogene- 

 tisk. Dette er saameget mere mærkeligt som For- 

 lioldet er et helt andet med Arterne af den meget 

 nærstaaende Slægt Et/IimcuUa, hvor Forplantningen 

 er udpræget bisexuel eller gamogenetisk, idet Han- 

 ner og Hunner til alle Tider synes at forekomme i 

 omtrent lige Antal. En Tid har jeg rigtignok staaet 

 i den Formening, at alle Individer af den her om- 

 handlede Phyllopode maaske kunde være hermaphro- 

 ditiske eller rettere protandriske, idet visse Forhold 

 ved Kjonsorganernes Bygning syntes mig at pege 

 i denne Retning; men Resultaterne af de af mig 



lo — G. 0. Sårs; Fauna Norvcoisc. 



gracious, undulatory motion. It is, on the whole, 

 very seldom that this swinging motion of the 

 branchial legs entirely ceases; for it happens only 

 when the animal is suddenly alarmed, in which case 

 all the parts of the body are withdrawn into the 

 shell, whicli then closes hermetically, and the animal 

 sinks to the bottom. The valves, however, very soon 

 reopen, and the fore part of the head, together with 

 the oars, is cautiously extended in front, and the 

 tail behind, whereupon the branchial legs recom- 

 mence their rhythmical swinging movements. 



The animal appears to feed principally on 

 broken portions of plants, unicellular algæ, and 

 possibly infusoria. These are whirled into the shell 

 by the movements of the branchial legs, and then 

 pass from back to front between the legs towards 

 the mouth. The mandibles are seen to be con- 

 stantly occupied in manipulating the food taken in 

 hj the mouth, which then, Ijy the aid of the nu- 

 merous muscles running from the labrum to the 

 æsophagus, is swallowed and introduced into the 

 anterior jiart of the intestine. Here the food under- 

 goes a preliminary process of dissolution liy the 

 intensely yellow secretion deposited by the liver. 

 Digestion seems on the whole to take place veiy 

 rapidly, the contents of the intestine quickly 

 changing colour as they pass backwards, from light 

 3'ellow or orange to a veiy dark brown or almost 

 black. At certain intervals the excrements are 

 ejected by the contractions of the rectum, often in 

 rather long, connected masses. As in the Branchi- 

 podidæ, energetic peristaltic movements may often 

 be observed in the walls of the intestinal tube. 



As stated above, all the specimens of this fox-m 

 hitherto observed, have proved, from their whole 

 appearance, to be females; and all specimens, 

 without exception, when they have attained to a 

 certain degree of development, are provided with 

 the characteristic cluster of eggs beneath the 

 dorsal part of the shell. Having observed this form 

 at difterent periods of the summer through a sei-ies 

 of years, and having also reared it repeatedl}- in 

 my acjuaria, where it has existed for months toge- 

 ther, I think I may declare with perfect certainty 

 that males in realit_y do not exist, and that the 

 propagation of tliis Phyllopod is thus exclusively 

 ])arthenogenetic. This is so much the more remark- 

 able, as the circumstance is altogether different in 

 the species of the very nearly-allied genus Ettli- 

 madia, where propagation is very markedly bi-sexual 

 or gamogenetic, males and females seeming at all 

 seasons to occur in about equal numbers. At one 

 time indeed, I was under the impression that all 

 the specimens of the Phyllopod in question might 

 perhaps be hermaphroditic, or rather protandric, as 

 certain circumstances in the structure of the sexual 

 organs seemed to me to point in that direction; 



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