129 



stillede Fortsatser, livoraf den midterste forestiller 

 Rostrum. 



Forekomst og Levevis. 



Det eneste Sted her i Landet, hvor denne Pliyllo- 

 pode hidtil er ohserveret, er i Østfinmarken ved 

 Matsjok, en Biflod til Tana, hvor Prof. Collett fandt 

 den i Sommeren 1885. Da jeg nogle Aar senere, i 

 1888, bereiste Finmarken, undlod jeg ikke at besøge 

 denne Lokalitet, og var ogsaa saa heldig at finde 

 den her i Slutningen af August meget almindeligt 

 i en grund, med talrige Vandplanter bevoxet Grøft. 

 Alle Exemplarer var da fuldt udviklede og syntes 

 at have opnaaet sit Maximum af Størrelse. Skjondt 

 jeg noie undersogte alle Damme og Grøfter i Om- 

 egnen, var det mig dog ikke muligt at finde noget 

 Spor af den andetsteds end netop i den omtalte 

 Groft, der saaledes maa have frembudt særlig gun- 

 stige Forhold til dette Dyrs Trivsel. 1 Lobet af. 

 nogle faa Dage indsamledes her et betydeligt Antal 

 Exemplarer, ligesom Observationer anstilledes over 

 det levende Dyr i mine Excursionsglasse. Dyrets 

 Bevægelser er temmelig klodsede og lidet udhol- 

 dende, bestaaende i et noget ujevnt og ligesom rul- 

 lende Lob gjennem Våndet, hvorunder snart Ryg, 

 snart Bug vendes opad. Under Bevægelsen er Ho- 

 vedet helt fremstrakt af Skallen, saa at Aarerue fuldt 

 kan virke, og Valvlerne er herunder vidt aabne neden- 

 til. Jeg kunde ikke observere, at Dyret nogensinde, 

 som Tilfældet er med Limnndia, fæstede sig til de i 

 Våndet værende Gjenstande. Naar Bevægelsen op- 

 horte, sank Dyret hurtigt til Bunden, og laa her 

 ofte i længere Tid ubevægeligt paa Siden, for saa 

 igjen at foretage en kort Udflugt i Våndet. Hanner 

 og Hunner forekom næsten i samme Antal og saaes 

 ofte i Copiilation, hvorunder Hannen med sine Gribe- 

 fodder med stor Kraft omfatter Kanterne af Hun- 

 nens Valvler nedentil. Selve Parringsakten fik jeg 

 dog ikke observere. At domme efter Kindbakkernes 

 Bevæbning, synes Dyrets Næring at være mere 

 animalsk end Tilfældet er med de øvrige bivalve 

 Phyllopoder, og bestaar rimeligvis for en stor Del 

 af mindre Entomostraceer. 



Udbredning. — Denne Phyllopode Idev forst 

 opdaget af 0. F. Muller i Damme nær Kjobenhavn, 

 og er ogsaa senere her gjenfuuden. Foruden i Dan- 

 mark er den observeret ved Danzig af Liévin, ved 

 Dorpat af Grube, i Lillerusland ved Charkow og i 

 Ungarn ved Pest, endelig ogsaa i Sibirien. I sin 

 Udbredning synes den saaledes idethele, i Modsæt- 

 ning til Limnadia, at være en østlig Form, og det 

 er aabenbart ad den Vei, nordenom den botniske 

 Bugt, at den har udbredt sig til vort Land. 



processes, the middle one of which represents the 

 rostrum. 



Occurrence and Habits. 



The only place in this country (Norway) where 

 this Phyllopod has hitherto been observed is in East 

 Finmark, near the Matsjok, a tributary of the Tana, 

 where Prof CoUett found it in the summer of 1885. 

 When some years later, in 1888, I travelled through 

 Finmark, I did not fail to visit this locality, and 

 had also the good fortune to find it there at the 

 end of August, very plentiful, in a shallow ditch 

 where numerous aquatic plants grevF. All the spe- 

 cimens were then fully developed, and seemed to 

 have attained their maximum size. Although I care- 

 fully examined all the ponds and ditches in the 

 neighbourhood, I did not succeed in discovering any 

 trace of it anywhere except in the said ditch, which 

 must thus have offered conditions especially favo- 

 rable to this animal's well-being. Li the course of 

 a few days, a considerable number of .specimens 

 were collected here, and observations made of the 

 living animal by watching them in my collecting- 

 jars. The animal's movements are rather awkward, 

 and not very persevering, consisting in a some- 

 what uneven and, as it were, rolling coiirse through 

 the water, sometimes with the dorsal, sometimes 

 vsdth the ventral side uppermost. During the 

 movement the head is stretched right out of the 

 shell, so that the oars can have their full effect, 

 the valves meanwhile being wide open below. 

 I never observed the animal attaching itself to 

 objects in the water, as is the case with Lim- 

 nadia. When the motion ceased, it sank quickly 

 to the bottom, and often lay there a long time on 

 its side, motionless, then again making a short ex- 

 ciirsion through the water. Males and females are 

 found in almost equal numbers; and are often seen 

 in copulation, during which the male, with its pre- 

 hensile legs, embraces with great power the lower 

 edges of the female's valves. The act of copulation 

 itself, however, I have not witnessed. Judging 

 from the armature of the mandibles, the animal's 

 food appears to be more animal than is the case 

 with the other bi-valve Phyllopoda, and probably 

 consists to a great extent of smaller Entomo.straca. 



Distribution. — This Phyllopod was first disco- 

 vered by 0. F. Mtiller, in ponds near Copenhagen, 

 and has also been found there again subsequently. 

 Besides in Denmark, it has been observed by Liévin 

 at Danzig, by Grube at Dorpat, at Chai-kow in 

 Little Russia, at Pesth in Hungary, and lastly in 

 Siberia. It therefore appears, in opposition to Lim- 

 nadia, to be, in its distribution, an eastern form, and 

 it is evidently by way of the north of the Gulf of 

 Bothnia, that it has spread to our land (Norway). 



17 — G. 0. Sars: Fauna Norvegix. 



