Ill 



i Septf'inlifT saiiiiiie Aar ni;- (ijiliolilt inii;- lier tra den 

 9de til (li'ii Ifide. rjimnadierne var nu meget sjeldne, 

 men adskilligt storre end de tidligere fundne, skjondt 

 ingen oversteg en Længde af 12 mm. Foruden i 

 det omtalte Tjern fandt jeg den ogsaa ])aa nogle 

 andre Steder af Øen, tildels i yderlig snnia 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 storre end de tidligere indsam- 

 lede. Sommeren 1888 fandt Prof. Collett denne 

 Pliyllo])ode paa en ganske anden Lokalitet, nemlig 

 i en liden Vandkulp i Nærheden af Hamar. For at 

 nnder.soge denne nye Lokalitet noiere, reiste jeg 

 derop den folgende Sommer i August, og jeg liavde 

 ikke synderlig Vanskelighed ved, efter Prof. Colletts 

 nærmere Angivelser, at tinde den omhandlede Kulji. 

 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 ]\Iud(ler for senere kunstige Udklæknings- 

 forsog. To (ilange senere har jeg liesogt den samme 

 Lokalitet, nemlig i Begyndelsen af Sejjtendier 1S'.»4 

 og i [Viidten af Juli 18U5. Begge (range fandtes 

 tilstra^kkeligt Vand i Kxilpen og store Mængder af 

 forskjellige Kntmno.straceer, men af Linuiadier var 

 der intetsomhelst Spor at opdage, hverken Larver 

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

 her er fuldstændig uddoet, for kanskc efter en lang 

 .\arrække paany at optræde ligesaa jilndselig som 

 den er forsvunden. Heller ikke af det kludder, der 

 l)aa disse 2 Udflugler medtoges fra Kulpen har jeg 

 kunnet udklække en eneste Limnadia. medens mine 

 mange Gange gjentagne Ldklækningsforsog med det 

 i 1881) samlede Mudder aldrig har slaaet feil. Idet- 

 hele synes, ogsaa efter andre Forskeres Beretninger, 

 denne Thyllojiodes Optræden at være yderst lune- 

 fnld. Lt Aar kan den trættes i stor.ste Misngde 

 paa et begrændset Omraade, for saa igjen sporlost 

 at forsvinde, og først efter lange Aarrækker kan 

 den saa optræde igjen entni paa samme Lokalitet 

 riler paa SttMler, li\-iir man tidligrri' aldrig har fun- 

 dfl den. 



Angaaendi' drnne l'\irnis !-i>v(;vis foroxi'igt, saa 

 synes overalt kun et enkelt K'uld Individi-r at ud- 

 vikle sig for hver Sommer. Man har ialfahl hidtil 

 ingen sikre I)ata for, al llere (ienerationer har tiilgt 

 paa hinandeu samnu; Aar. Jndividernes Livs])eriode 

 synes i IJegelen kun at va're indskræidvet til et 

 L\ir Maaneder, ofte kanske iklve engang saa henge. 

 l\Ien i Lol)et af denne korte Tid vil ialfald en Del 

 ^af ludividerne uaa til Kjonsmodenhed og kunne af- 



largest specimens were ahout ID mm. lung, and iiad 

 5 pairs of liiu's of growth. In ordei- to rind, if ])os- 

 sible, full-grown specimens, 1 again visited the island 

 in Septendier of the same year, and stayed there 

 from the '.Hh tn the l.")tli. Tiie Limnadix were then 

 very rare, hut considerahiy larger than those pre- 

 viously fiiund, although none exceeded a length of 

 12 mm. 1 also fonnd it in other phices on the 

 islaiul hesides the ahove-mentioned lake, sometimes 

 in exceedingly small ai'cnmulations of water, though 

 then cif a smaller size. On the other iiand it was 

 not to he found on a single one of the many sni-- 

 rounding islands. In the tollowing year also, 1 

 found this form again in the heginning of August 

 in the same places, hut none larger than those ])re- 

 viously taken. In the summer of 1888, Prof, ('(dlett 

 found this Pliyllojiod in ipiite another locality, 

 namely in a little ]i(iol in the neighhoui'liood of 

 Hamar. In order tn examine this new locality 

 more minutely, I went nj) there the following sum- 

 mer in Atxgust, and, from Prof. Colletts exact des- 

 cription, had udt mui'h difriculty in finding the ]io(d 

 in ijuestion, It was however completely diied up, 

 owing to the pi-,'eediiig lung ])erind of dry weather, 

 so that all 1 iMuild do was tn take away with me 

 some of the drie(l mud, in urder to attemj)t arti- 

 ficial Imtcliing at a future time. Twice snhse- 

 quently have I revisited the same locality, namely, 

 in the heginning of Sojitemher. ISU4 and in the 

 middle of duly, 18115. Hotli times I fcmnd sufricient 

 water in the jxifd. and large nundiers of variims 

 Entomostraca, hut nu trace of Linnuulia was to be 

 discovered, whether larva i>r adult, sn that it ahnost 

 apjiears as it' it were nnw comjiletely extiiu't, j)er- 

 ha])s to a])pear again aftci- a numbei' of years as 

 suddenl\- as it has disajipeared. Xor \-et have I 

 succeeded in hatching (uu' single Limnadia out of 

 the nutd bronglit away from the po(d on these 

 two excursions, while m\- oft-repeated hatching 

 attempts with the mud c(dlected in 188U have never 

 failed. It seems. (Ui the whole, as also fi'om the 

 accounts of other lutturalists, that the appearance 

 of this I'hyllopod is i>xtrenudy capricious. One year 

 it may be met with in large numbers over a limited 

 area, then vanish utterly, ami only after nuiuy 

 years nuiy appear again, either in the same loca- 

 litv, or in jdaces where it has never lieen found 

 previously. 



^\'ith regard tu the haliits of this form in 

 other resj)ects, it always appears that only a single 

 brood of animals is develo])ed each summer, ^\'e 

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

 tain data to jirovi! that several generations have 

 succeeded one anotiiei' in the same year. The living 

 jieriod of the indivi<lual animals seems as a rule to 

 be limited to a cou]de of months, freipiently perhaps 

 even less. Hut in the course of this slmrt time 



