oe 
65- 
Det tidligste Larvestadium, jeg har fundet, er | 
afbildet Tab. IX, Fig. 7. Det svarer, hvad Lem- 
mernes Udyikling angaar, noget ner til det Tab. 
VIII, Fig. 15 afbildede Stadium af Branchinecta, 
men skiller sig meerkeligt derved, at de sammen- 
satte Mine, der hos hint Stadium neppe endnu var 
anlagte, her er meget tydeligt og omtrent ligesaa 
vidt komne som paa det i andre Henseender meget 
videre udviklede Stadium af Branchinecta, som er 
fremstillet Fig. 17 paa samme Planche. Det synes 
altsaa som om disse Organer udvikles betydelig tid- 
ligere hos nerverende Phyllopode. De 2 Par Fo- 
lere og Kindbakkerne med sine Palper stemmer idet- 
hele meget noie med samme hos det tilsvarende 
Stadium af Branchinecta, alene med den Forskjel, at 
den inderste af de 2 fra 2det Par Foleres Skaft ud- 
gaaende, indadkrummede Fortsatser her er simpel, 
ikke tvekloftet. Af Branchialfodder er der kun til- 
Stede 7—8 svage Anleg i Form af simple Tver- 
vulster til hver Side af Kroppen, som allerede viser 
en tydelig Segmentering. Haleenden er noget ind- 
snoret yed Basis og ender med 2 meget korte Lappe, 
hver berende en enkelt Borste. 
Den videre Udvikling foregaar paa en fuldkom- 
men lignende Maade som hos Branchinecta, idet 
Branchialfodderne successivt udvikles forfra bagtil, 
medens 2det Par Folere 08 Mandibularfodderne grad- 
vis reduceres. 
Forekomst og Levevis. 
Nerverende eiendommelige Phyllopode er meget 
almindelig overalt i Finmarken. Jeg har truffet 
den paa folgende Lokaliteter: Bugo paa Sydsiden 
af Varangerfjorden, Vadso, Fastlandet indenfor 
Vardo paa mange Stedet, Vagge Tanafjord, Mehavn, 
Hasvig paa flere Steder, Hammerfest ligesaa. Leen- 
gere Syd paa Landet har jeg derimod aldrig stodt 
paa den, og den synes saaledes hos os udelukkende 
at vere indskrenket til den arktiske Zone. Den 
forekommer under lignende Forhold som Branchi- 
necla paludosa og ikke sjelden sammen med den. 
Det er iser i ganske grunde Smaatjern med mudret 
Bund og som ud paa Sommeren delvis eller fuld- 
‘stendig udtorres, at den paatreeffes og her ofte i 
enorme Mengder. Dog har jeg ogsaa af og til truf- 
oa den i storre og dybere Vande, f. Ex. i et Tjern 
a Hoideplateanet ved Vagge i Bunden af Tana- 
en, hvor den viste en vakker blaalig Farve- 
- a Den svommer ialmindelighed om i Vandet 
_ mere eller mindre ner Overfladen og med en ganske 
_ jevn Fart, altid med Ryggen nedadvendt. Hanner 
Hunner treeffes meget ofte i Copulation, og Han- 
fastholder herunder Hunnen saa kraftigt med 
e Gribeantenner om Kjonsregionen, at det ikke 
9 — G. 0. Sars: Fauna Norvegizx. 
The earliest larval stage that I have found is 
figured on Pl. IX, fig. 7. As regards the develop- 
ment of the limbs, it answers to the stage of Bran- 
chinecta represented on Pl. VIL, fig. 15, with the 
remarkable difference that the compound eyes, which, 
in that stadium, had scarcely commenced to appear, 
are here very distinctly developed, and are about 
as far advanced as in the, in other respects, much 
further developed stadium of Branchinecta shown on 
fig. 17 of the same plate. It therefore seems as if 
these organs were developed much earlier in the 
present Phyllopod. The two pairs of antenne and 
the mandibles with their palpi agree on the whole 
very exactly with those organs in the corresponding 
stage of Branchinecta, with the one difference, that 
the inner of the two incurved processes starting 
from the scape of the second pair of antenne 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 distinct articulation. The ex- 
tremity of the tail is somewhat constricted at the 
base, and ends in two very short lobes, each carrying 
a single bristle. 
Further development proceeds exactly as in 
Branchinecta, the branchial legs developing succes- 
sively from front to back, while the 2nd pair of 
antenne and the mandibular legs gradually di- 
minish. 
Occurrence and Habits. 
This peculiar Phyllopod is very common over 
the whole of Finmark. I have met with it in the 
following localities: Bugs, on the south side of the 
Varanger Fjord; Vadso; in many places on the 
mainland south of Varde; Vagge on Tana Fjord; 
Mehavn; Hasvig in many places; also Hammerfest. 
On the other hand, I have 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 conditions as, and not infre- 
quently together with Branchinecta paludosa. It is 
especially in quite shallow, small lakes with muddy 
bottom, and which either partly or completely dry 
up towards the end of the summer, that it is met 
with, and there often in very great numbers. I have, 
however, now and then also found it in larger, 
deeper lakes, e. g. in a lake on the plateau at 
Vagge, at the head of Tana Fjord, where it was of 
a beautiful blue colour. It generally swims about 
more or less near the surface of the water at an 
even rate, and with its back always turned down- 
wards. Males and females are often found in copu- 
lation, during which the male clasps the female so 
firmly with its prehensile antenne about the genital 
