38 



rende Dyrs lidet faste Integumenter, der nejjpe er 

 egnede til at opbevares i fossil Tilstand. Dog maa 

 det her bemærkes, at det langt fra er sikkert, at 

 alle de ældgamle, fordetmeste siluriske Fonner, der 

 af Packard henregnes til Phylloeariderne, virkelig 

 hører herhen. Enkelte af dem har ialfald habitiielt, 

 ved sit iiade Rygskjold og tildels Mangelen af den 

 for Phylloeariderne characteristiske Pandeplade, en 

 vel saa stor Lighed med notostrake Phyllopoder 

 (Apiis), og kan derfor muligvis ligesaa sandsynligt 

 have hørt 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 ægte Phyllopoder er Indlandsfornier og 

 forekommer som oftest i ganske smaa og grunde 

 Ferskvandsansamlinger, der om Sommeren ganske 

 eller delvis ndtørres. Arterne ai Slægten Arfemia 

 er eiendommelige for det stærkt saltholdige Vand i 

 de saakaldte Saliner. I Havet exi.sterer der derimod 

 for Tiden ingen Phyllopoder. 



Angaaende disse Dyrs Foi'plantningsmaade og 

 Udvikling, saa stoder vi her paa mange eiendomme- 

 lige og interessante Forhold, ligesom deres sporadiske 

 Forekomst, Udbredningsforhold og Levevis idethele 

 frembyder yderst mærkværdige Ting, som neppe 

 endnu er tilstrækkeligt forklaret. Naar hertil kom- 

 mer deres ofte meget bizarre Udseende, elegante Be" 

 vægelser og eiendommelige Organisation, synes der 

 virkelig at være Grund for med Packard at anse 

 dem for de interessanteste af alle Crnstaceer. 



Skjondt der til Norges Fauna kun liorer ialt 

 5 Former, er dog alle de 3 ovennævnte Hovedgrup- 

 per repræsenterede, og enhver af de norske Former 

 repræsenterer desuden for sig en særskilt Familie. 



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 habitiis, by their flat carapace and partly 

 from the absence of the frontal plate characteristic 

 of the Phyllocarida. a rather stronger resemblance 

 to notostracan Phyllo]iods (Apus), and may therefore 

 just as probably have possibly pertained thereto. 

 As we do not know the appendages from any of 

 these fossil fonns, 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 Arfeniia 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 cru- 

 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. 



