rende Dyrs lidet faste Integumenter, der neppe er 
egnede til at opbevares i fossil Tilstand. Dog maa 
det her bemerkes, at det langt fra er sikkert, at 
alle de eldgamle, fordetmeste siluriske Former, der 
af Packard henregnes til Phyllocariderne, virkelig 
horer herhen. Enkelte af dem har ialfald habituelt, 
ved sit flade Rygskjold og tildels Mangelen af den 
for Phyllocariderne characteristiske Pandeplade, en 
vel saa stor Lighed med notostrake Phyllopoder 
(Apus), og kan derfor muligvis ligesaa sandsynligt 
have hert herhen. Da man af ingen af disse fossile 
Former kjender Lemmerne, maa deres rette syste- 
matiske Stilling endnu blive at betragte som et 
aabent Spergsmaal. 
Alle egte Phyllopoder er Indlandsformer og 
forekommer som oftest i ganske smaa og grunde 
Ferskvandsansamlinger, der om Sommeren ganske 
eller delvis udtorres. Arterne af Slegten Artemia 
er eiendommelige for det sterkt saltholdige Vand i 
de saakaldte Saliner. I Havet existerer der derimod 
for Tiden ingen Phyllopoder. 
Angaaende disse Dyrs Forplantningsmaade og 
Udvikling, saa stoder vi her paa mange eiendomme- 
lige og interessante Forhold, ligesom deres sporadiske 
Forekomst, Udbredningsforhold og Levevis idethele 
frembyder yderst merkverdige Ting, som neppe 
endnu er tilstrekkeligt forklaret. Naar hertil kom- 
mer deres ofte meget bizarre Udseende, elegante Be 
vegelser og eiendommelige Organisation, synes der 
virkelig at vere Grund for med Packard at anse 
dem for de interessanteste af alle Crustaceer. 
Skjondt der til Norges Fauna kun horer ialt 
5 Former, er dog alle de 3 ovenneyvnte Hovedgrup- 
per representerede, og enhver af de norske Former 
representerer desuden for sig en serskilt Familie. 
38 
and most original Phyllopods. We arrive in that way 
at, rather, a quite contrary conclusion, namely that 
that group is of considerably younger origin than 
the 2 others. That we are ignorant of any prime- 
val forms of these lastnamed groups may be natur- 
ally explained by the little firm nature of the inte- 
guments of the animals pertaining hereto, which are 
scarcely adapted for preservation in fossil condition. 
Still it must be noted here that it is far from cer- 
tain that all the ancient, chiefly silurian forms, 
which are assigned by Packard to the Phyllocarida, 
really pertain thereto. A few of them have, at any 
rate, in habitus, by their flat carapace and partly 
from the absence of the frontal plate characteristic 
of the Phyllocarida, a rather stronger resemblance 
to notostracan Phyllopods (Apus), and may therefore 
just as probably have possibly pertained thereto. 
As we do not know the appendages from any of 
these fossil forms, their correct systematic position 
must still be considered an open question. 
All genuine Phyllopods are inland forms, and 
usually appear in quite small and shallow collections 
of fresh-water, which in summer quite, or partially, 
dry up. The species of the genus Artemia is peculiar 
to the strongly salt water in the so-called salines. 
In the ocean there exist, on the other hand, at the 
present time, no Phyllopods. 
Regarding the method of reproduction of these 
animals and their development, we come here upon 
many peculiar and interesting relations, while also 
their sporadic appearance, distributive relations, and 
mode of life upon the whole, present extremely 
remarkable things which are scarcely yet suffici- 
ently elucidated. When to this is added their fre- 
quently very bizarre appearance, the elegance of 
their movements and the peculiar ‘organisation, there 
seems really to be reason for, like Packard, consi- 
‘dering them to be the most interesting of all ern- 
staceans. 
Although there only pertain 5 forms altogether 
to the fauna of Norway, the 3 above named chief 
groups are, however, all represented; and each of 
the Norwegian forms represents of itself, besides, a 
separate family. ' 
