Ill 



i September samme Aar og ophoklt mig lier fra den 

 9(le til den lode. Limnadierne var nu meget sjeldne, 

 men adskilligt storre end de tidligere fundne, skjondt 

 ingen oversteg en Længde af 12 mm. Fortiden i 

 det omtalte Tjern fandt jeg den ogsaa paa nogle 

 andre Steder af Øen, tildels i yderlig smaa Vand- 

 ansamlingér, dog her af mindre Størrelse. Derimod 

 fandtes den ikke paa en eneste af de mange omlig- 

 gende Øer. Ogsaa det følgende Aar gjenfandt jeg 

 denne Form i Begyndelsen af August paa de samme 

 Steder, men ingen storre end de tidligere indsam- 

 lede. Sommeren 1888 fandt Prof. Collett denne 

 Pliyllopode paa en ganske anden Lokalitet, nemlig 

 i en liden Vandkulp i Nærheden af Hamar. For at 

 undersoge denne nye Lokalitet nøiere, rei.ste jeg 

 derop den folgende Sommer i August, og jeg havde 

 ikke synderlig Vanskelighed ved, efter Prof. Colletts 

 nærmere Angivelser, at tinde den omhandlede Knip. 

 Den var imidlertid nu fuldstændig udtorret paa 

 Grund af længere Tids forudgaaende tort Veir, saa 

 jeg alene kunde forsyne mig med noget af det ind- 

 torrede Mudder for senere kunstige TJdklæknings- 

 forsøg. To (xange senere har jeg besøgt den samme 

 Lokalitet, nemlig i Begyndelsen af September 1894 

 og i Midten af Juli 1895. Begge Gange fandtes 

 tilstrækkeligt Vand i Kulpen og store Mængder af 

 forskjellige Entomostraceer, men af Limnadier var 

 der intetsomhelst Spor at opdage, hverken Larver 

 eller voxne, saa det iiæsten ser ud til, at den nu 

 lier er fuldstændig uddoet, for kan.ske efter en lang 

 Aarrække paany at optræde ligesaa pludselig som 

 den er forsvunden. Heller ikke af det Mudder, der 

 jiaa disse 2 Udflugter 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. Idet- 

 hele synes, ogsaa efter andre Forskeres Beretninger, 

 denne Phj-llopodes Optræden at være yderst lune- 

 fuld. Et Aar kan den træifes i største Mængde 

 paa et begrændset Omraade, for saa igjen sporløst 

 at forsvinde, og først 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 iiaa til Kjonsmodenhed og kunne af- 



large.st specimens were about 10 mm. bmg, and had 

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

 sible, full-grown specimens, I again vi.sited the island 

 in September of the same year, and stayed there 

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

 very rare, l)ut considerably larger than those ])re- 

 viously found, although none exceeded a length of 

 12 mm. 1 also found it in other places on the 

 island besides the above-mentioned lake, sometimes 

 in exceedingly small accumulations of water, though 

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

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

 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 quite 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 August, and, from Prof. Collett's exact de.s- 

 cription, had not much difticulty in finding the pool 

 in question, It was however completely dried up, 

 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 subse- 

 quently have I revi.sited the same locality, namely, 

 in the beginning of September, 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 years as 

 suddenly as it has disappeared. Nor yet have I 

 succeeded in hatching one single Limnadia out of 

 the mud brought away from the pool 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. 



With regard to the habits of this form in 

 other respects, it always appears that only a single 

 brood of animals is developed each summer. We 

 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 



