hr> 



Det tidligste Larvestadium, jen- liar fuiidet, er 

 afbildet Tali. IX, Fig. 7. Det svarer, hvatl Lem- 

 raernes 1'dvikliiig angaar. iioget næi' til det Tab. 

 VIII, Fig. 15 atliildede Stadium af JBrancJiiiiPCfa, 

 men skiller sig nuerkeligt derved, at de sammen- 

 satte f tine, der hos hint Stadium neppe endnu var 

 anlagte, lier er meget tydeligt ng omtrent ligesaa 

 ^•idt komne som paa det i andre Henseender meget 

 videre udvildede Stadium at' Branchmccta, som er 

 fremstillet Fig. 17 paa samme Planr-he. Det synes 

 altsaa som om disse Organer udvikles Ijetydelig tid- 

 ligei'e hos nærværende Phvllo])ode De 2 Par Fø- 

 lere og Kiudliakkerne med sine Palper stemmer idet- 

 hele meget noie med samme lios det tilsvarende 

 Stadium aH Bmiichinecfn, alene med den Forskjel, at 

 den inderste af de 2 fra 2det Par Foleres Skaft ird- 

 gaaende, indadkrummede Fortsatser her er simpel, 

 ikke tvekloftet. Af Braneliialfodder er der kun til- 

 stede 7 — S svage Aiiheg i Form af simple Tvær- 

 vnlster til liver Side afKrop])en, som allerede viser 

 en tydelig Segmentering. Haleenden er noget ind- 

 snoret ved Basis og ender med 2 meget korte Lappe, 

 hver bærende en enkelt Rorste. 



Den videre Udvikling foregaar jiaa en fuldkom- 

 men lignende MaaJe som hos Bnuichinecta, idet 

 Branchialfodderne suceessivt udvikles forfra bagtil, 

 medens 2det 1'ar Fcdere og Mandibularfodderne grad- 

 vis reduceres. 



Forekomst os,' LeveTis. 



Nærværende eiendommelige Phyllojiode er meget 

 almindelig overalt i Finmarken. .leg har truffet 

 den paa folgende Lokaliteter: Bugo ])aa Sydsiden 

 af A'arangerfjorden. A'adso, Fastlandet indenfor 

 Vardø paa juange Stedet, Vagge Tanafjnrd, Mehavn, 

 Hasvig paa dere Steder, Hammerfest ligesaa. Læn- 

 gere Syd paa Landet har jeg derimod aldrig stodt 

 ]iaa den, og den synes saaledes hos os udelukkende 

 at være indskrænket til den arktiske Zone. Den 

 forekommer under lignende Forhold som Braiichi- 

 neda paludosa og ikke .sjelden sammen med den. 

 Det er især i ganske grirnde Smaatjern med mudret 

 Bund og som ud ])aa Sommeren delvis eller fuld- 

 stændig udtorres. at den paatræftes og her ofte i 

 enorme Mængder. I>og har jeg ogsaa af og til truf- 

 fet den i større og dybere Vande, f. Ex. i et Tjern 

 ])aa Høideplateauet ved Vagge i Bunden af Taua- 

 fjorden, hvor den viste en vakker blaalig Farve- 

 tegning. Den svommer ialmindelighed om i Våndet 

 mere eller mindre nær Overfladen og med en ganske 

 jevn Fart, altid med Ryggen nedadvendt. Hanner 

 og Hunner trætfes meget ofte i ( 'opulation, og Han- 

 nen fastholder herunder Hunnen saa kraftigt med 

 sine (Iribeantenner om Kjon.sregionen, at det ikke 



'.I — (j. *■). Sars : Fauna Xorvefiicr. 



The earliest larval stage that I have found is 

 figured on PI. IX, tig. 7. As regards the develop- 

 ment of the limlis, it answers to the stage ot Bran- 

 chiiiecta represented on PI. VIII, tig. 15, with the 

 remarkable ditt'erenee that the compound eyes, which, 



\ in that stadium, had scarcely commenced to ajipear, 

 are here very distinctly developed, and are about 

 as far advanced as in the, in other respects, much 

 further develo]ied stadium i\\' BrancMnecta shown on 

 tig. 17 of the same plate. It therefore seem.s as if 

 these organs were developed much earlier in the 

 present Phyllopod. The two pairs of antennæ and 

 the mandibles with their ])alpi agree on the whole 

 verv exactly with those organs in the corresjionding 



j stage of Branchinecta , with the one difference, that 

 the inner of the two incurved processes starting 

 from the scape of the second paii' of antennæ are 

 here simple, not bifid. There are only 7 or 8 slight 

 rudiments of branchial legs in the form of simple 

 transverse prominences on each side of the body, 

 which already shows di.stinct articulation. The ex- 

 tremity of the tail is somewhat constricted at the 

 base, and ends in two very short lobes, each carrying 



j a single lu'istle. 



Further development proceeds exactly as in 

 Brancliinecta, the branchial legs develojjing succes- 

 sively from front to back, while the 2nd pair of 

 antennæ and the mamliliular legs graduall\' di- 

 minish. 



Ot'ciirreiioe and Habits. 



This pei.'uliar Ph\-Il()pod is very common over 

 the whole of Finmark. 1 have met with it in the 

 following localities: Bugo, on the south side of the 

 Varanger Fjord; Vadsø; in many places on the 

 mainland south of Vardø; Vagge on Tana Fjord; 

 Mehavu; Hasvig in many places; also Hammerfest. 

 (.)n the other hand, I liave never come across it 

 further south, and it thus seems, in this country 

 (Norway) to be confined to the arctic zone. It is 

 found under the same renditions as, and not infre- 

 ([uentlv together with Branchhiecta pahulosa. It is 

 especiallv in quite shallow, small lakes with muddy 

 bottom, and which either jiartly or completely dry 

 up towards the end of the summer, that it is met 

 with, and there often in very great numbers. 1 have, 

 however, now and then also found it in larger, 

 dee])er lakes, e. g. in a lake on the plateau at 

 Vagge, at the head of Tana Fjord, where it was of 

 a lieautiful blue colour. It generally swims alitiut 

 more or less near the surface of the water at an 

 even rate, and with its liack always turned dowu- 

 Avards. Males and females are often found in co])u- 

 lation, during which the male clas])s the female so 

 firmly with its prehensile antennæ about the genital 



