Subordo I. 



PHYLLOCARIDA 



(Leptostraca, Claus). 



Character. — Branchiopoder med deu forreste 

 Del af Legemet dækket af et stort, m.ere eller min- 

 dre ixdpræget tveklappet Rygskjold, forsynet fortil 

 med en bevægelig Pandeplade. Den bagre Del af 

 Kroppen cylindrisk, afsmalnende bagtil og endende 

 med 2 bevægelige Grene (Furca), meil em hvilke der 

 undertiden er en dolkformig Haleplade. Øinene stil- 

 kede og bevægelige. Begge Par Folere vel udviklede, 

 mangeleddede, 2det Par enkle, hverken locomotoriske 

 eller prehensile. Alle Forkropslemmer bag Mund- 

 delene udelnkkende respiratoriske ; Bagkropslem- 

 merne meget ulig disse og fordetmeste locomotoriske, 

 manglende paa de bagerste Segmenter. Havdyr. 



Alm. Bemærkninger. — Typen for denne Under- 

 orden er den i mange Henseender høist mærkvær- 

 dige og anomale Slægt Nebalia, om hvis systematiske 

 Stilling der har hersket den storste Uenighed blandt 

 Zoologerne. Medens man før ialmindelighed med 

 Milne-Edwards henregnede denne Form til Phyllo- 

 iwderne, har i den nyere Tid, navnlig efter de af 

 Prof. Claus anstillede Undei^søgelser, en ganske anden, 

 allerede meget tidligt af enkelte Naturforskere ytret 

 Opfatning vundet Overhaand, nemlig at denne Form 

 slutter sig nærmest til de stilkoiede Krebsdyr, navn- 

 lig til visse Schizopoder (Euphausiidæ), og at den 

 saaledes snarere tilhorer Malacostraceernes Afdeling 

 end Entomostaceerne. .S^g har paa et andet Sted ') 

 nærmere udviklet mine Grunde til fremdeles at bi- 

 beholde denne Slægt under Entomostraceerne, og 

 blandt disse er Branchiopoderne de, hvormed nær- 



Sub-Order I. 



PHYLLOCARIDA 



(Leptostraca, Claus). 



Characters. — Branchiopods, with the foremost 

 portion of the body covered by a large, more or 

 less distinctly bi-lobate carapace, furnished anteri- 

 orly with a mobile frontal plate. The posterior por- 

 tion of the body cylindi'ieal tapering backwards, and 

 terminating in 2 mobile rami (furca), between which 

 there is occasionally a mitcroniform caudal plate 

 Eyes pedunculated and mobile. Both pairs of antennæ 

 well developed, multiai'ticulate; 2nd pair simple, 

 neither locomotory nor prehensile. All the appen- 

 dages of the anterior division of the body behind 

 the oral parts, exclusively respiratorj'. The appen- 

 dages of the posterior division of the body very 

 unlike the former and chiefly locomotorj'; absent 

 on the posterior segments. Marine animals. 



General remarks. The tj'pe of this sub-order 

 is — the in many respects highly remarkable and 

 anomalous genus — Nebalia, regarding whose sys- 

 tematic position the greatest difference of opinion 

 has prevailed among zoologists. Whilst, previously, 

 zoologists in general agreed with Milne-Edwards 

 in assigning this form to the PhyUopods, there has 

 prevailed in later times, especially since the result 

 of 'the investigations made by Prof. Claus, a 

 quite different opinion, which alread}^ much earlier 

 'was expressed by a few naturalists, viz: that this 

 form approximates closest to the stalk-ej'ed Crusta- 

 ceans, especiallj'^ to certain Schizopods (Eu]jhausiidæ), 

 and that it, therefore, pertains rather to the Malaco- 

 stracan than to the Entomostracan division. I have 

 elsewhere*) explained, in greater detail, my reasons 

 for still retaining this genus under the Entomo- 



') Report ou the Phyllocarida, collected during theExpfilition 

 of H. M. S. ^Challenger.. 



') Report on the Pliyllocaridn collected during the Expedition 

 of I-I. M. S. -Cliallenser». 



