Ill 



i September samme Aar op; o])liol(lt mig her fra den 

 ikle til (len 15de. Limiiadierne var im meget sjeldne, 

 men adskillig! storre end de tidligere fundne, skjondt 

 ingen oversteg en Længde af 12 mm. Foruden i 

 det omtalte Tjern fandt jeg den ogsaa paa nogle 

 andre Steder at' Øen, tildels i yderlig smaa Vand- 

 ansamlinger, dog her af mindre Storrelse. Derimod 

 fandtes den ikke paa en eneste af de mange omlig- 

 gende Øer. Ogsaa det folgende Aar gjenfandt jeg 

 denne Form i Begyndelsen af August paa de samme 

 Steder, men ingen stoi-re end de tidligere indsam- 

 lede. Sommeren 1888 fandt Prof, follett denne 

 Phyllopode paa en ganske anden Lokalitet, nemlig 

 i en liden Vandkulp i Nærlieden af Hamar. For at 

 imdersoge denne nye Lokalitet noiere, reiste jeg 

 derop den folgende Sommer i August, og jeg havde 

 ikke synderlig A^anskelighed ved, efter Prof. Colletts 

 nærmere Angivelser, at finde den omhandlede Kulp. 

 Den var imidlertid nu fuldstændig udtorret paa 

 (xrund af længere Tids forudgaaende tort Veir, saa 

 jeg alene kunde forsyne mig med noget af det ind- 

 torrede Mudder for senere kunstige Udklæknings- 

 forsog. To (lange senere har jeg hesogt den samme 

 Lokalitet, nemlig i Begyndelsen af September 1894 

 og i Midten af Jiili 1895. Begge Gange fandtes 

 tilstrækkeligt Vand i Knipen og store Mængder af 

 forskjellige Entomostraceer, men af Limnadier var 

 der intetsom helst Spor at opdage, hverken Larver 

 eller voxne, saa det næsten ser ud til. at den nu 

 her er fuldstændig uddoet, for kanske efter en lang 

 Aarrække paany at optræde ligesaa pludselig som 

 den er forsvnnden. Heller ikke af det ]\[udder, der 

 paa disse 2 UdUugter medtoges fra Kulpen har jeg 

 kunnet udklække en eneste Limnadia, medens mine 

 mange Gange gjentagne Udklækningsforsog med det 

 i 1889 samlede Mudder aldrig har slaaet feil. Llet- 

 hele synes, ogsaa efter andi-e Forskeres Beretninger, 

 denne Phyllopodes Optræden at være yderst lune- 

 fuld. Et Aar kan den træftes i storste Mængde 

 paa et begrændset Omraade, for saa igjen sporlost 

 at forsvinde, og forst efter lange Aarrækker kan 

 den saa optræde igjen enten paa samme Lokalitet 

 eller paa Steder, hvor man tidligere aldrig har fun- 

 det den. 



Angaaende denne Forms Levevis forovrigt, saa 

 synes overalt kun et enkelt Kuld Individer at ud- 

 vikle sig for hver Sommer. Man har ialfald hidtil 

 ingen sikre Data for, at flere Generationer har fulgt 

 paa hinanden samme Aar. Individernes Livsperiode 

 synes i Regelen kun at være indskrænket til et 

 Par Maaneder, ofte kanske ikke engang saa længe. 

 Men i Lobet af denne korte Tid vil ialfald en Del 

 af Lidividerne naa til Kjonsmodenhed og kunne af- 



largest specimens were about 10 mm. long, and iiad 

 5 pairs of lines of growth. In order to find, if pos- 

 sible, full-grown specimens, I again visited the island 

 in September of the same year, and stayed there 

 from the 9th to the 15th. The Limnadix were then 

 ver3' rare, but consiclerably larger than those pre- 

 vioush^ found, although none exceeded a length of 

 12 mm. I also found it in other places on the 

 island liesides the above-mentioned lake, sometimes 

 in exceedingly snmll accumulations of water, thoiigh 

 then of a smaller size. On the other hand it was 

 not to be found on a single one of the many sui'- 

 rounding islands. In the following year also, I 

 found this form again in the beginning of August 

 in the same places, but none larger than those pre- 

 viously taken. In the summer of 1888, Prof. Collett 

 found this Phyllopod in r|uite another locality, 

 namely in a little pool in the neighbourhood of 

 Hamar. In order to examine this new locality 

 more minutely, I went up there the following sum- 

 mer in Attgust, and, from Prof. Collett's exact des- 

 cription, had not much difticulty in finding the pool 

 in ipiestion. It was however completely dried u}), 

 owing to the preceding long period of dry weather, 

 so that all I could do was to take away with me 

 some of the dried mud, in order to attempt arti- 

 ficial hatching at a future time. Twice svibse- 

 quently have I revisited the same locality, namely, 

 in the beginning of Septeml)er, 1894 and in the 

 middle of July, 1895. Both times I found sufficient 

 water in the pool, and large numbers of various 

 Entomostraca, but no trace of Limnadia was to be 

 discovered, whether larva or adult, so that it almost 

 appears as if it were now completely extinct, per- 

 haps to appear again after a number of yeai's as 

 suddenly as it has disappeared. Nor yet have I 

 succeeded in hatching one single Limnadia out of 

 the mud brought away from the jiool on these 

 two excursions, while my oft-repeated hatching- 

 attempts with the mud collected in 1889 have never 

 failed. It seems, on the whole, as also from the 

 accounts of other naturalists, that the appearance 

 of this Phyllopod is extremely capricious. One year 

 it may be met with in large numbers over a limited 

 area, then vanish utterly, and only after many 

 years may appear again, either in the same loca- 

 lity, or in places where it has never been found 

 previously. 



A\'itli regard to the haluts of this form in 

 other respects, it always appears that only a single 

 brood of animals is developed each summer. A\'e 

 have not, at any rate up to the present, any cer- 

 tain data to prove that several generations have 

 succeeded one another in the same year. The living- 

 period of the individual animals seems as a rule to 

 be limited to a couple of months, frequently perhaps 

 even less. But in the course of this short time 



