-4'/ Hl 1. > Æ^' ^ ^^ -1^ .N- i-if»*^ \' '*. : t*' >--< ■-"^-■^ ''i^ '••' .'■V'^*^: -* •■». :i^^!^ié^-.>^ fWicorJTitidJÉf Km DIVISION MARINE QTVBETfiBRATB» CARDED >i< '°^3iii3M FAUNA NORYEGIÆ Bd. I. BESKRn"ELSE AF DE HIDTIL KJENDTE NORSKE ARTER AF UXDERORI )XERXE PHYLLOCARIDA og PHYLLOPODA VEI) i/ERTEBRATE { G= O. SARS \ ZOOLOGY Crustacea IIB ^ A I Y MED 20, TILDELS FARVETRYKTE I'LANCHER CHRISTIANIA TRYKT I AKTI E-BOGTR Y K KE R I ET (Forhen: Det Mallingske Bogtrykkeri.) 1896 v\ FAUNA NORVEGIÆ Vol. I. DF.SCHIPTIo.XS ()F THK X( •KW'l'.dlAX Sl>l-:(;iF.S AT PHESKXT KX(n\'N BELONGING To THl-: STB-oRDERS PHYLLOCARIDA and PHYLLOPODA BY G. O. SARS WITH 20 PLATES. COLOURED AND UXCOLOURED CHRISTIANIA PRINTED BY THE JOINT-STOCK PRINTING COMPANY (Formerly: Det MalliDgske Bogtrykkeri.) 1890 FORTALE. PREFACE. Nærværende Værk, til hvis Ildgivel^ie Staten liar bevilget de fornodne Midler, blev paabegyiidt for mere end et Decenniiira siden; men forskjellige uforudseede Omstændigheder bar bevirket, at Ud- ai'beidelsen af samme i længere Tid har maattet standses, saa at forst nu Værket kan ndkomme i sin Helhed. (Jprindelig var Bevillingen givet til den fortsatte Udgivelse af Fauna litforalis Norregiæ, hvoraf tidligere er irdkommet 3 Bind, forfattede dels af min Fader alene, dels af barn i Forening med nu afdode Overlæge Danielssen og Konservator Koren. Da det forekom mig, at denne Titel paa en mindre beldig Maade vikle komme til at begrændse Stoffet, tillod jeg mig at foreslaa, at Benævnelsen littoralis ndgik og at Værket berefter skulde nd- komme under den ber anvendte Titel. Det af mig til nærværende Bind valgte Stof er ogsaa af den Art, at det vanskeligt vikle passe indenfor Rammen af den tidligere Titel, da jo ber ikke blot Sodyr, men ogsaa en Del ægte Ferskvandsdyr er omhand- lede. Idethele syntes mig, at den mere omfattende Titel, Fauna Non-egier, bedre maatte kunne svare til sin Hensigt, da der herunder vil kunne leveres Bidrag til Belysning af bvilkensomhelst Branclie af vor Fauna, der maatte frembyde en særlig Interesse. I Overensstemmelse med de 3 udkomne Bind af Fauna littoralis, tror jeg at nærværende Værk bor indeholde Afbandlinger af en mere udforlig ana- tomisk-biologisk Character, behandlende visse ud- valgte Dele af vor Fauna og udstyrede paa en saa- vidt nraligt tidsmæssig Maade, saavel hvad Text som rianeber angaar. I et andet, paa engelsk .skre- vet Værk har jeg paabeg^-ndt en Bearbeidelse af vor Fauna efter et herfra temmelig torskjelligt Prin- eip, idet dette Værk er nærmest Iberegnet paa at The pi'esent '\\-iirk, for the publication of which the (lovernment has granted the necessary funds, was begun more than ten years ago ; but various unforeseen circumstances having combined to put a stop to the ]ireparation of the work for a considerable time, it is only now that it can he published in its entirety. The grant was originally given for the continued publication of Fauna littoralis Norvegiæ, of which three vohimes had already been published, written pai"tly by my father alone, partly by him in conjunction with the late Dr. Danielssen, and Curator Koren. As it seemed to me that this title would Kmit the subject-matter somewhat infelicitously, I ventured to suggest that the desig- nation litforalis should be struck out, and that the work should hereafter appear under the title here em])lo_\-ed. The matter chosen by me for the pre- sent volume, is also of such a kind, that it could hardly be included under the former title, as not only marine animals, but also some true fresh-water animals are here treated of. Upon the whole, it seemed to me that the more comprehensive title. Fauna Norvegiæ, would better answer its jiurpose, as under it, contributions might be made to the infor- mation concerning any branch (if our fauna that might offer special interest. In accordance with the 3 published volumes of Fauna littoralis, I think that the present work should contain treatises of a more exhaustive anatomical-biological character, dealing with certain parts of our fauna, and got up as far as possible in a manner suitable to the times, as regards text and plates. In another work, written in English, I have begun an account of our faiina on a very dift'erent principle to this, as it is rather calculated to give, as far as possible, a brief, VI give en saavidt muligt kortfattet systematisk Over- sigt af samtlige hidtil kjendte norske Arter, hvor- ved der er lagt hovedsagelig Vægt paa dets prak- tiske Anveudeliglied ved Artsbestemm eisen, mindre paa det 3-di'e Udst\T eller paa en mere indgaaende anatomisk Behandling af de enkelte Former. Jeg tror, at zoologiske Arbeider udarbeidede efter ethvert af disse Principer har sin fulde Berettigelse og Nytte Side om Side, og skulde ogsaa af denne Grund onske, at Fauna Norvegio? blev forbeholdt mere udforlige Monograpliier af enkelte mindre kjendte Dyreformer eller af begrændsede Grrupper, der maatte frem- byde en særlig Interesse i anatomisk-biologisk Hen- seende. Plancherne til nærværende Bind er i sin Tid udforte paa nu afdode Lithograf Lynglis Officin, og ved deres Udforelse er anvendt al den Omhyggelig- hed og Kunst, som da kunde jiræsteres, saavel hvad Lithographering som Farvetrykning angaar. Texten er i Lighed med de 2 sidste Bind af Fauna littoralis og med Nordhavs-Expeditionens Generalberetning, dobl)eltspaltet, den ene Spalte norsk, den anden en- gelsk. Oversættelsen af de 6 forste Ark er besørget af nu afdode Translateur Wilson, Resten af Miss Jessie Miiir. Idet jeg herved fremlægger for Offentligheden Iste Bind af Fauna Isorvegiæ, sker det med det Haab, at der maa gives vore fremtidige Zoologer Anledning til at fortsætte dette Værk med flere paafolgende Bind udstyrede paa en for vort Land værdig Maade. Forfatteren. systematic survey of all the hitherto known Nor- wegian species, whereby special importance is laid on its practical applicability in the determination of species, and less on its external get-up. or on a more detailed anatomical treatment of the various forms. I think that zoological works written on these two principles are perfectlj- legitimate and useful side by side ; and I therefore wish that Fauna Norvegiæ could be kept for more detailed mono- graphs on certain less familiar animal forms, or of limited groups that offered special interest in an anatomical-biological direction. The plates to the present volume were executed, in their time, in the late lithographer Lyngh's printing-office, and all the care and art of which that time vs^as capable, both as regards lithography and colour-printing, were employed in their execu- tion. The letter-press is similar to that of the last 2 volumes of Fauna littoralis^ and to the General Report of the North Atlantic Expedition, being in two columns, the one column Norwegian, the other Eng- lish. The translation of tlie first 6 sheets was made by the late Mr. Wilson, translator, the remainder by Miss Jessie Muir. In now presenting the first volume of Fauna Norvegiæ to the public, I do so in the liojie that opportunity may be given to our future zoologists to continue this work with successive volumes, got up in a manner worthy of our country. The Author. INDHOLD. Pag-. IiicUi'ilnini;' 1- PhyUocar ida 4. F am. Nebaliidm 6. Oen. Nehalia, Loach V. 1. Nehalia hipes iFabr.) '■>■ 2. Xehalia typlilnps, G. (). Sars 31. Fliyllopoda 35. Seciio I. Anostraca :)9. Fam. 1. Branchipodidæ 40. (icn. Branchinecta, \'errill 40. Branohinecta paludosa Miiller) 41. Fam. 3. Poly arte mii dee -^8. Geii. Polyartemia, Fischer 58. Piilyartciuia forcipata, Fischer 59. Secfio II. Notostraca m. Fam. Apodidæ . 67. Gen. Lepidwus, Leacli 67. Lepiilunis glai-iahs ICroyer) 68. Sectio III. Conchos traca 83. Fam. 1. LimnadlidcB 84- Gen. Limnadia. Broguiart 85 Limnadia lenticularis Lin.) 85 Fam. 2. Limnetidæ 116 Gon. Limnetis. Loven 116. Linmctis braclivurus ilnll.) 117. CONTENTS. Pag. Introilnction 1. PhyUocar ida 4. Fam. Nebaliidm 6. (xen. Nebalia, Leach 7. 1. Xehalia bipes fFahr.- 9. 2. Xeluilia typhlnps, G. O. Sars 31. Phyllopoda 35. Section I. Anostraca 39. Fam. 1. Branchipodidæ 40. (ren. Brancliinecta, Verrill 40. Brancliinccta palmlosa Miiller") 41. Fam. 3. Poly art em iidce 58. (Ten. Polyartemia, Fischer 58. Pdlyartemia forcipata, Fischer 59. Section II. Notostraca 66. Fam. Apodidæ 67. (^en. Lepidurus, Leach ()7. Lcpidunis glacialis Krøyer) (iS. Section III. Conchostraca 83. Fam. 1 Limnadiidæ 84. C-ien. Limnadia, Brogniart 85. Limnadia lenticularis (Lin.j 86. Fam. 3. Limnetidæ 116. Gen. Limnetis, Loven 116. Limnetis lirachvurus Miill.) 117. INDLEDNING. Crustaeeernes vidtloftige Classe inddeles, som bekjendt, ialmindelighed i to store Afdelinger, Mala- costraca, eller de høiere Krebsdyr, og Eviomosfraca, eller de saakaldte Smaakrebse. Enhver af disse Afdelinger lader sig igjen dele i 4 Grupper eller Ordener. Til den forste hører 1) Podophfhalmata, eller de stilkoiedeKrebse (Decapoda, Schizopoda og Stomatopoda), 2) Cwiiacea, 3) Isopocla og 4) Amphi- po(la\ til den sidste: 1) Branchiopoda, 2) Ostracoda, 3) Cirripedia, og 4) Copepoda. Hertil kommer endnii den i mange Henseender meget anomale, og i visse Punkter med Arachniderne beslægtede Gruppe, Xlpho- miræ, eller Dolkhalerne, som dog af flere Natui-- forskere ikke henregnes til Crustaceerne, men be- tragtes som Typen for en egen Arthropodeclasse. Naar undtages denne sidste Gruppe, er alle de øvrige ovenauforte Ordener vel repræsenterede i vor Fauna. . For det forste vil vi alene komme til at be.skjæftige os med den første af de til Entomostra- ceerne horende Ordener, Branchiopoda. Denne Orden har faaet sit Navn deraf, at et storre eller mindre Antal af de bag Munddelene følgende Lemmer an- tager en eiendommelig bladdannet Structur, der gjør dem fortrinlig skikkede til at fungere som Respira- tionsorganer, om de end i enkelte Tilfælde paa samme Tid kan fungere som Svømmeapparater. Undertiden, saaledes hos visse Cladocerer, kan disse Lemmers saavel respiratoriske som motoriske Func- tion være meget reduceret, hvorimod de faar sin væsentligste Betydning som Griberedskaber, der understotter Munddelene ved at fastholde og bringe til Munden de Fodemidler. hvoraf disse Dyr lever, en Function, som imidlertid ogsaa for en Del kan paavises hos Former med forovrigt normalt udvik- lede Branchialfqdder, f. Ex. Ajjus. Ogsaa hos fuld- 1 — G. 0. .Sårs: Faunn Korvegix. INTRODUCTION. As is known, the extensive class Crustacea is, in general, classified into two great divisions viz., Malacostraca, or the higher Crustaceans, and En- tomostraca. or the so-called lower Crustaceans. Each of those divisions may be si^bdivided, again, into 4 groups or orders. To the first division per- tain; — 1) PodoplUhalmatd or the stalk-eyed Crusta- ceans (Decapods, Schizopods and Stomapods), — 2) Cmnacea, — 3) Isopoda, and — 4) Amphipoda. To the second division pertain : — 1) Branchiopoda, — 2) Ostracoda, — Cirripedia, and — 4) Copepoda. To them is added the Xiphosurcn, or sword-tails — in many respects very anomolous, and in certain cha- racters r el at- d to the group Arachnida — which are by several naturalists, however, not assigned to the Crustaceans, but is considered to be the type of a special class af Arthropods. With the excep- tion of tliat last-named group all the other above- mentioned orders are well represented in the Nor- wegian Fauna. At present we shall only occupy ourselves with the first of the orders pertaining to the Entoniostracans viz : Branchiopoda. This order has obtained its appellation from the circumstance, that a larger or smaller number of the appendages behind tlie oral parts assume a peculiar foliaceous structure, which causes them to be admirably adapted to serve as respiratory organs, even although they, in a few cases, may at same time serve as swimming apparatuses. Occasionally, as in certain Cladocerans, both the respiratory and motoric func- tions of these appendages may he greatly diminished; and their essential importance becomes that of a prehensile-apparatus which aids the oral parts in securing and carrying to the moiith the nutriment upon which these animals feed; a function which kommen typiske Braiiclaiopoder vil vi finde, at Lem- merne, ved Siden af sin Function som Respirations- organer, altid er af væsentlig Betydning for Til- veiebringelsen af Foden, idet de ved sine rythmiske Bevægelser frembringer en pontinuerlig Stromning af Våndet ind mod Mnnden, hvorved de Smaa- partikler, hvoraf Dyret lever, bringes indenfor Mund- delenes Omraade. I ethvert Fald maa den oven- omtalte eiendommelige Modification af Lemmerne, hvortil vi egentlig ikke har noget tilsvarende hos andre Crustaceer, betragtes som den for de her om- handlede D_yr vigtigste og mest udprægede Cha- racter. Branchiopoderne indtager i tiere Henseender en central Stilling inden Crustaceernes Classe, og Prof. Claus har endog fremsat den Hypothese, at alle nulevende Crustaceer i sidste Instans nedstammer fra en phjdlopodeagtig Dyreform (Protophyllopod). Skjondt denne Hypothese af andre Zoologer (Packard) har været bestridt, er der dog al Grund til at an- tage, at disse Dj^r har conserveret adskillige Cha- racterer, der efter al Sandsynlighed er i hoi Grad primitive og raaaske endog skriver sig fra de ældste paa vor Klode optrædende Arthropoder. Allerede det i hoi Grad varierende og ofte excessivt forøgede Antal Kropssegmenter, samt disses ialmindelighed mindre skarpt udprægede Gruppering til distincte Kropsafsnit, synes at vise, at vi her har at gjore med Former af en kun lidet udarbeidet Character, hos hvem endnu ikke det for Nutidens Crustaceer typiske Forhold rigtigt har fæstnet sig; og hvad Lemmernes Bj'gning angaar, saa er vel alle enige i at de, ialfald hos de tj-piske Branchiopoder, repræ- senterer et mere primitivt Standpunkt end hos nogen af de ovrige Crustacegrupper. Ogsaa hvad den indre Organisation angaar, findes hos de herhen horende Former kun lidet iixerede Forhold, men derimod en Mangfoldighed af Modificationer i Bygningen af snart sagt alle Organer, hvad der ligeledes giver denne Crustacegruppe et ganske eiendommeligt Præg lige- overfor de ovrige Ordener. Endelig vil vi i disse Dyrs Levevis, Forplantning og Udvikling stode paa baade characteriske Forskjelligheder mellem de for- skjellige Former og tildels ogsaa hoist eiendomme- lige, fra samme hos andre Crustaceer afvigende For- hold. Et nøiere Studium af denne Crustacegruppe vil derfor ogsaa være af særlig Interesse, saavel i phylogenetisk som biologisk Henseende og vil pas- sende kunne tjene som Udgangspunkt ved Bearbei- delsen af den lier omhandlede Dyrclasse. may also, to some extent, be demonstrated in forms with otherwise normall}' developed branchial-legs e. g. Apns. Also in perfectly typical Branchiopods we may observe that the appendages, besides their function as respiratory organs, are always of mate- rial importance in the procuring of the nutriment, as they by their rhythmical movement produce a continuous current of the water in towards the mouth, by which the minute particles upon which the animal exists are brought within the range of the oral parts. At any rate, the above mentioned peculiar modification of the appendages, to which we meet with nothing really correspondent in other Crustaceans, must be considered to be the most important and prominent characteristic of the ani- mals here spoken of. The Branchiopods occupy, in several respects, a central position in the class of the Crustaceans, and Pi'of. Claus has even proposed the hypothesis, that all the now-existent Crustaceans may descend, in the final instance, from a phyllopodous animal-form (Protophyllopod). Although that hypothesis has been rejected by other zoologists (Packard), there is still every reason to assume that those animals have retained several characteristics which are, in all probalaility in a high degree primitive, and perhaps even emanate from the oldest Arthropods that have appeared on our Earth. The extremely vari- able and frequently excessively increased number of bodj'-segnients, as well as in general their less distinctly prominent grouping into distinct sections, at once appears to point to the circum- stance that we have here to do with forms of only vaguely developed character, in which the typical fea- tures characteristic of the modernly existent Crusta- ceans, have not j^et become permanently established : and as regards the structure of the appendages all unite, we believe, in the opinion that it. at any rate in the ty])ical Branchiopods, represents a more jiri- mitive condition than in any of the other groups of Crustaceans. Also in regard to the internal or- ganization there is found, in the forms belonging to this order, only little of permanent features but, on the other hand, a multitude of modifications in the structure of, it may be said, all the organs, a circumstance that also imparts to this group of Crustaceans a quite peculiar imprint compared with the other orders. Finally we meet in these ani- mals' mode of life, projiagation and development, ! both characteristic dilferences between the various ' forms and parti}', also, highl}' peculiar features ' difi^ering from those in other Crustaceans. A closer study of this group of Crustaceans will, therefore, prove of special interest, both in phylogenetic and biological respects, and will serve as a suitable point of departure in the treatment of the animal- class here spoken of. Brancliiopodernes Orden lader sig naturligt ind- dele i 4 underordnede Grupper, eller Underordener, der saavel livad den ydre Habitus som den anato- miske Bygning angaar, skiller sig temmelig skarpt fra liinanden. Disse Underordener er følgende: 1) Phijllo- carida, 2) Fhytlopoda, 3) CJadocera og 4) Branchiura. De 2 første af disse Underordener vil blive gjorte til Gjenstand for en nøiere Behandling i nærværende Bind af Fauna Norvegiæ. The order of Branchiopods may be naturally divided into 4 subordinate groups or sub-orders, which, both in regard to external habitus and ana- tomical structure, distinguish themselves pretty sharply from each other. These sub-orders are, as follows viz : 1) Phi/Uocarida, — 2) FhyUopoda^ — o) CJadocera, and — 4) Brancliiura The two first- named sub-orders will be made the subject of a closer treatment in the present volume of Fauna Norvegiæ. 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». flfj^^ ^ g^lfei** værende Form viser mest Åfinitet. At den imid- lertid ikke længere kan opfattes som en virkelig Phyllopode, derom kan der vel neppe for Tiden være mere end en Mening, efterat dens anatomiske Byg- ning, navnlig ved Prof. Claus's ndmærkede Under- søgelser, er bleven noiere udredet Sporgsmaalet er nu, om de Eiendommeliglieder, denne Form viser i anatomisk Henseende, gjor det absolut nodvendigt at skille den helt ud fra de ovrige Entomostraceer som Typen for en egen Orden. Saagodtsom samtlige Forskere synes for Tiden i Virkeligheden at være af denne Mening, og baade Packard's Benævnelse PhyUocarida og den af Claus foreslaaede Leptostraca er beregnet paa at udtrj-kke en distinct Orden. Undersoger vi imidlertid, hvorledes Forholdet er med de for Tiden ialmindelighed til Branehiojiodex'nes Orden henførte Former, saa vil vi ogsaa her stode paa særdeles store og væsentlige Forskjelligheder i den anatomiske Bj^gning; ja de saakaldte7?;Y(Hf7(» demarcation between the foremost and hindmost sections. Ej'es more or less developed, each covered at the base by an acuminate squamiform plate. Superior antennæ snorter than the inferior ones; peduncle 4-jointed with a strong geniculate bend 8 simpelt triangulært Fremspring; det lamelleformige Vedhæng ovalt, tæt haaret; Svoben hos Hannen mere forlænget end hos Hunnen og forsynet med talrige krandsformigt stillede Sandsebørster. De nedre Folere med Skaftet 3-leddet, 2det Led ved Enden fertil gaaende ud i et kort tandformigt Frem- spring og dannende med sidste Led en knæformig Bøining; Svøben hos Hannen overordentlig tynd og forlænget. Kindbakkernes Palper meget store, 3-leddede, sidste Led sammentrykt, lineært, stiunpt tilrundet i Enden og tæt borstebesat langs Inder- kanten. Iste Par Kjæver med begge Tyggelappe korte, den yderste bredest, Palpen stærkt forlænget, besat med lange stive Børster; 2det Par med vel udviklet 2-leddet Palpe og smal elliptisk Exognath. Branchialfodderne ganske dækkede af Rygskjoldets Valvler; Endopoditen jevnt afsmalnende mod Enden, hos Hunnen stærkere forlænget end hos Hannen samt ved Spidsen besat med lange, cilierede Børster; Exopoditen lamelleformig, bredt oval; Epipoditen meget stor, pladeformig, saavel oventil som nedentil uddraget til en lamellær Lap. Svømmefødderne kraftigt udviklede, den ydre Gren kortest og i Yderkanten hevæbnet med stærke Torner, den indre smalt lancetformig. Halegrenene lineære, stærkere forlængede hos Hannen, tæt børstebesatte langs Inderkanten og i Spidsen. Bemærkninger. — Fra de 2 ovennævnte Slæg- ter, Faranebalia og Nchalicpsis, er nærværende Slægt, fornden ved Branchialfoddernes forsk] elligeUdseende, blandt andet characteriseret ved Rygskjoldets Form, som navnlig hos Slægten Nebaliopsis er temmelig afvigende, fremdeles ved de eiendommelige skjæl- formige Øienplader, ved Følernes B3'gning og navn- lig disses eiendommelige Udvikling hos Hannen, ende- lig ved Kjævernes Bygning. Ogsaa i det indbyrdes Forhold mellem de forskjellige Kropsafsnit er der characteristiske Differentser mellem de "å Slægter. — Man kj ender for Tiden med Sikkerhed kun 2 Arter af denne Slægt, som begge forekommer hos os ■ og nedenfor vil lilive noiere beskrevne M. ') Den af Thomson (Ann. Nat. Hist. Ser. 5. Vol. 4), fra JSew Zeeland anførte N. longicornis tør flog, efter Lokaliteten at domme, repræsentere en egen Art. Det afbildede Ex- emplar, en fuldt udviklet Han, lii,'uer imidlertid sa^rdeles meget Hannen af vor N. hipes. between the 2nd and 3rd joints; last joint somewhat expanded towards the extremity and, anteriorh% produced to a short plain triangular projection ; the lamelliform appendage oval, densely hirsute ; Hagellum in the male more prolonged than in the female, and furnished with numerous verticilate sensory bristles. Inferior antennæ with the peduncle 3-jointed, 2nd joint, af the anterior extremity, produced to a short dentiform projection, and forming with the last joint a geniculate bend ; flagellum in the male extremely slender and prolonged. Mandibular palps very large, 3-jointed, last joint compressed, linear, bluntly rounded at the extremity, and closely beset with bristles along the inner edge. First pair of maxillæ with both masticatory lobes short, the outer one broadest, palp greatly prolonged, beset with long stiff bristles; 2nd pair with well developed 2-jointed palp and small elliptical exognath. Branchial legs quite covered by the valves of the carapace, the endopodite diminishing uniformly towards the ex- tremity, more prolonged in the female than in the male, and at the extremity beset witli long ciliated bristles; the exopodite lamelliform, broadly oval; the epipodite very large, lamelliform, drawn out above and below to a lamellar lappet. Natatory legs powerfully developed, the outer ramus shortest and on the outer margin beset with strong spines; the inner ramus narrow lanceolate. Caudal rami linear, more prolonged in tlie male, closely beset with bristles along the inner edge and at the tijj. Remarks. — The present genus is, besides by the diiterent appeai-ance of the branchial legs, among other things distinguished from the 2 above-men- tioned genera, Faranehalia and Nebaliopsis, by the form of the carapace, which, especially in the genus Nehaliopsis is pretty different; further, by the pecu- liar squamiform ocular plates, the structure of the antennæ and especially their peculiar development in the male, and finally by the structure of the maxillæ. In the mutual relations, also, between the various sections of the body, there are charac- teristic divergencies betweeri the 3 genera. At present we know, with certainty of onl3- 2 species of this genus, both of which belong to the Norwe- gian Fauna and will be more particularly described in the sequel '). ') N. longknrnh mentioned Ijy Thomson, from Xew Zealand, (Ann. Nat. Hist. Ser. 6, Vol. 4) may, however, judged by its locality, represent a distinct species. The specimen illustrated, a fully developed male, resembles, however, very greatly the male of the northern N. hipes 1. IVebalia bipes (Fabr). (Tab. I, Fig. 1—3; Tab. II ug III; Tab. IV, Fig. 1—8; Tab. V). Cancer hipes, 0 Fabricius, Fauna Gronlandica n. 223. Cancer ganiarellus bipes, Herbst, Geschichte der Krabben etc. II, ni. Xehnlia Herhsfii, Leach, Zool. miscell. I, p. 100. — — Milne— Edwards. Hist. nat. des Crustacea. Ill, p. 356. Nehalia Montagu!, Tliompson, Zool. Kesearches. Nehalia hipes, Krøyer, Groulands Amphipoder, p. 91. — — Naturh. Tidsskr. 2den Række, II, p. 430. — — Gaimard's Voyage en Scandinavie, PI. 40, Fig. 2, a — X. — — Baird, British Entomostraca. Nehalia Geoff'royi, Milne — Edwards, Ann. d. sc. nat. 1828. — — M— Edwards, Hist. nat. d. Orustacés. III. — — Clans, Zeitschr. f.wissensch. Zoologie, XXII, p. 323, Tab. XXV. — — Glaus, Untersuchungen zur Erforschuug der genealogischen Grundlage des Crustaceen- systeins, p. 24, Tab. XV, Fig. 4—6. Nehalia bipcs, A. S. Packard, A JMonograph of the Phyllopod Crustacea of North America, with Remarks on the Order Phyllocarida, p. 432, PI. XXXVI— XXXVII. Artscharacter. — Legemet af temmelig slank Form, navnlig bos Hannen. Eygskjoldet af betyde- lig Størrelse, seet fra Siden lios Hnnnen af oval, bos Hannen af elliptisk Form, omtrent lige bøit fortil som bagtil. Pandepladen jevnt tilrnndet i Enden, uden terminal Spina. Øinene vel ndyiklede, noget sammentrykte, med den ydre Del noget ud- videt og skjævt afrundet, Pigmentet af mørkerød Farve. De ovre Følere bos Hunnen omtrent af For- kroppens Længde, med Svoben omtrent saa lang som Skaftet og det lamelleformige Vedbæng ovalt; bos Hannen betydelig stærkere forlængede, med Svøben mere end dobbelt saa lang som Skaftet og det lamelleformige Vedbæng smalt elliptiskt. De nedre Følere hos Hunnen Va Gang til aaa lange som de øvre; bos Hannen af bele Legemets Længde, med Svøben overordentlig tynd og forlænget. Branchial- foddernes Epipodit meget stor, elliptisk, med den nedre Lap af samme Størrelse som den ovre. Iste Par Svømmefodder med Yderkanten af den ydre Gren tandet i hele sin Længde. Halegrenene bos Hunnen omtrent saa lange som de 2 sidste Bagkrops- segmenter tilsammen, bos Hannen af mere end den dobbelte Længde. Farven varierende fra lyst bvid- gult til intensiv rodbrun. Legemets Længde indtil 12 mm. Bemærkninger. — Den middelbavske Form, N. Geoffroyi, M. Edvv., bvoraf jeg bar havt Exem- plarer til Undersøgelse, tagne af min Fader ved Neapel, synes i ingensombelst Henseende at skille sig fra vor nordiske Form, der utvivlsomt er iden- tisk med Fabricius's Art. Det samme er ogsaa Til- fældet med N.Merhsfii Leacb og N. Montagui Thomp- - — t^. 0. Sars: Fauna Norvegiæ. Nehalia Nehalia Nehalia Nehalia 1. Nebalia bipes (Fabr) (Pl. I, figs. 1—3; ri. II and III; Pl. IV. figs. 1-8;. Pl. V.). Cancer hipes, 0. Fabricius, Fauna GrOnlaudica n. 223. Cancer ganiarellus hipes, Herbst, Geschichte der Krabben &c II, III. Nehalia Herhsfii, Leach, Zool. miscell. I. p. 100. — — Milne-Edwards, Hist. nat. des Crustacés, III. p. 356. Montagui, Thompson, Zool. Kesearches. hipes, Kroyer, CTrnnlands Amphipoder, p. 91. — Xaturh. Tidsskr. 2 Series, II, p. 436. — Gaimard's Voyage en Scandinavie, Pl. 40, fig. 2, a— x. — Baird, British Entomostraca. Geoff'royi, Milne— Edwards, Ann. de sc. nat. 1828. JI-Edwards, Hist. nat. d. Crustacés, III. Claus, Zeitschr. f. wissensch. Zoologie, XXII, p. 323, Pl. XXV. Claus, Untersuchungen zur Erforschung der genealogischen Grundlage des Crustaceen- systems, p. 24, Pl. XV, fig. 4—6. hipes, A. S. Packard, A Monograph of the Phyllopod Crustacea of North America, with Remarks on the order Phyllocarida p. 432, PI. XXXVI- XXXVII. Specific characters. — Body of rather slender form, especiallj^ in the male. Carapace of consider- able size, viewed laterally in female oval, in male ' elliptical in form, about the same height in front as behind. Frontal plate evenly rounded at the extremity, without terminal spina. Eyes well deve- loped, somewhat compressed, with the outer part somewhat expanded and obliquely rounded, pigment of dark red colour. Superior antennæ in female about the length of tlie anterior division of the l)ody, with the flagellum about as long as the pe- duncle and the lamellar appendage oval; in male considerably more prolonged, with the flagellum more than twice as long as the peduncle, and the lamelliform appendage narrow elliptical. Inferior antennæ in female half again as long as the superior ones; in male as long as the entire body, with the flagellum extremely thin and prolonged. Epipodite of the branchial legs very large, elliptic, with the lower lobe of same size as the upper one. First pair of swimming legs dentated along the entire length of tbe exteroir edge of the outer ramus. Caudal rami in female about as long as tbe 2 last seg- ments of tbe posterior division of the body together; in male more than twice tbe length. Colour vary- ing from light wbity -yellow to intense red-brown. Length of the body reaching 12 m. m. Remarks. — The Mediterranean form, X. Geoffroyi, M.Edw. of which I have bad specimens for investi- gation, collected by my father off Naples, appears in no respect, whatever, to distinguish itself from our northern form, which is, undoubtedlj', identical with Fabricius's species. Tbe same is also the case with N. HerhsUl Leach, and JS. Montagu/ Tlnjmpson. 10 son. Overhovedet synes kun denne ene Art at være observeret af andre Forskere. Fra den følgende meget nærstaaende, skjendt sikkert speoifiskt for- skjellige Form er den strax kjendelig ved de vel udviklede og med tydeligt Pigment og Synselementer forsynede Øine, samt ved Pandepladens forskjellige Form. Beskrivelse af Hunnen. Legemets Længde, regnet fra Spidsen af Pande- pladen til Enden af de sammenlagte Halegrene, er Los de største af mig ohserveredeExemplarer, tagne ved Lofoten, omtrent 1"2 mm. Exemplarer fra vor Syd- og Vestkyst er ialmindelighed noget mindre. Legemets Form (se Tab. I, Fig. 1 og 2) maa idetliele siges at være temmelig slank, især naar man observerer Dyret i levende Tilstand. Paa de i Spiritus opbevarede Exemplarer synes ialmindelig- lied Legemet noget kortere og mere undersætsigt paa 'Grnnd af en ved Spiritusens Action frembragt kjendelig Contraction i Ledføiningerne mellem de forskjellige Segmenter; noget der ogsaa bemærkes paa de fleste af andre Forskere givne Figurer af dette Dyr. Hele den forreste Halvpart af Legemet dækkes mere eller mindre fuldstændigt af Rygskjol- det, bag hvilket den bagtil successivt afsmalnende og meget bevæ.gelige Hale rager frit frem. Den habituelle Lighed med en Copepode (navnlig visse Herpacticider) er umiskj endelig og bliver endmere paafaldende, naar man observerer Dyret i levende Tilstand, idet Bevægelserne foregaar paa en fuld- kommen lignende Maade. Rygskjoldet er meget stærkt samraentrykt fra Siderne, saa at dets Brede kun lidet overgåar den halve Høide, og, da det desuden mellem sine Side- dele fuldstændig indeslutter ikke blot Munddelene, men ogsaa alle følgende Forkro])slemmer (Pranchial- fødderne), har det mere Lighed med en tveklappet Skal, saaledes som vi linder det hos visse Phyllo- poder og Cladocerer. Ogsaa i andre Henseender er denne Lighed tydeligt fremtrædende. Saaledes vil man finde, at dette Rygskjold kun paa et meget indskrænket Omraade helt fortil og oventil, dan- ner den umiddelbare Kropsvæg (se Tab. IL Fig. 1), medens det forøvrigt kun gan.ske løst dækker Le- gemet, som derfor frit kan bevæges indenfor samme. Endelig kan de 2 Sidedele, eller Val vier, ligesom hos de ovennævnte Branchiopoder, bevæges imod hinanden ved Hjælp af en stærk transversal Ad- ductormuskel (Tab. IL Fig. 7, ms), der lige liag Munddelene forbinder de 2 Valvler med hinanden. Insertionen af denne Adductormuskel er ogsaa ud- vendigt meget tydeligt at se i den forreste Del af hver Valvel, nærmere Dorsalsiden, i Form af en vel begrændset oval Area, hvori bemærkes en Ansam- Altogethei-, only this single species appears to have been observed by other investigators. From the following very closely related, although certainly specifically different, form, it is immediately distin- guishable by the -well developed eyes furnished with distinct pigment and visual elements, and also by the different form of the frontal plate. Description of the female. The length of the body measured from the tip of the frontal plate to the extremity of the folded caudal rami is, in the largest specimens that I have observed, taken off Lofoten, about 12 mm. Specimens from the south and west coasts of Norway are generally somewhat smaller. The form of the body (see PI. I fig. 1 and 2) must be said to be, on the whole, rather slender, especially when the animal is obsei'ved in the liv- ing state. In specimens preserved in alcohol, the body appears, in general, to be somewhat shorter and stouter, owing to an appreciable contraction of the articulations between the various segments, pro- duced by the influence of the alcohol, a circumstance also noticed in the illirstrations of this animal sup- plied by most other naturalists. The entire fore- most half of the animal is covered more or less completely by the carapace, behind which the grad- ually backwards-diminishing and very mobile tail projects freely. The habiti^al resemblance to a Copepod (especially certain Harpaeticids) is unmis- takeable and becomes still more conspicuous when we observe the animal in the living state, as the movements occur in an exacth' similar manner. The carapace is very strongly compressed from the sides, so that its breadth Imt little exceeds half the height, and, besides, as it completely encloses between its lateral parts not only the oral parts but also all the succeeding appendages of the anterior division of the body (the branchial legs), it has more of resemblance to a bivalve shell, such as we find it in certain Phyllupods and Cladoceres Also in other respects is this resemblance distinctly pro- minent. We may thus observe that this carapace forms, only within a very limited space quite in front and above, the immediate wall of the body (see PI. II fig. 1), whilst it, otherwise, only quite loosely covers the body, which can therefore move itself freely within it. Finally, the 2 lateral parts or valves can, as in the above-mentioned Branchio- pods, be moved towards each other with the aid of a powerful transversal adductor muscle (see PI. 11 fig. 7, ms.) which immediately behind the oral parts connects the 2 valves to each other. The insertion of this adductor muscle may also be very distinctly observed from the exterior, in the foremost part of each valve next the dorsal side, in tlie form of 11 ling af klare Pletter (lucid spots), svarende til de enkelte Bundter af Adductormuskelen (se Fig. 1 ms). Nogen virkelig Laasrand, saaledes sora hos Ostra- coderne og enkelte Phyllopoder (Estheria, Limnetis), er imidlertid ikke tilstede, idet de 2 Valvler dorsalt gaar iimærkeligt over i hinanden med en jevn Krum- ning. Seet fra Siden (Tab. I, Fig. 1) har Rygskjoldet en noget uregelmæssig oval, eller næsten rhombisk Form, med omtrent samme Hoide fortil som bagtil. Rygkanten er ganske svagt buet og danner med de skraat afskaarne bagre Kanter en meget stump Vin- kel. Fortil udgaar fra Rygskjoldet øverst den be- vægelige Pandeplade, som i denne Stilling tager sig \iå som et tilspidset, noget nedadboiet Pandehorn. Imellem denne og de forreste, noget udbuede Kanter af Rygskjoldet er der et smalt Indsnit, hvorfra (Hnene rager frem. De nedre Kanter er i sin for- reste Del stærkt l)uede, længere bagtil næsten lige, og forbinder sig under en stærk Krumning med de bagre Kanter, livorved fremkommer til hver Side en afrundetSidelap, der næsten rækker lige til Enden af Bagkroppens 4de Segment. Ovenfra seet (Fig. 2) viser Rygskjoldet sig meget smalt og stærkere af- smalnende fortil end bagtil, hvor det har en dyb, i Bunden smalt afrundet median Indbugtning, der skiller de 2 Sidelappe fra hinanden. Ved den for- reste Ende af Rygskjoldet sees Pandepladen, som nu viser en smal tungedannet Form, med Enden jevnt afrundet (se ogsaa Tab. II, Fig. 2). Den er forbundet med Rygskjoldet ved et tydeligt Led, saa at den ved særegne Mviskler kan snart rettes lige fortil, snart indbøies mod Forkanten, i hvilket Til- fælde den ligesom et Laag dækker fortil for Ind- gangen til Rygskjoldets Hule. Rygskjoldet er gan- ske glat, uden nogen tydeligt udpræget Sculptur og uden Børster eller Torner, af temmelig tynd, boielig, chitinøs Consistens og halvt gjennemsigtigt, saa at den indenfor liggende Krop tilligemed dens Lemmer kan skimtes igjennem samme. For noiere at kunne undersøge denne sidste, er det imidlertid hensigtsmæssigt at fjerne den ene af Ryg.skjoldets Valvler ise Tab. II, Fig. 1). Det viser sig da, at Legemet i sin hele Længde er tydeligt segmenteret, og at Segmenterne grupperer sig til vel markerede Kropsafsnit. Man kan ialt adskille 4 saadanne Afsnit, hvoraf de 2 tilhører Forkroppen, de 2 øvrige Bagkroppen. Det forreste Afsnit af Forkroppen kan passende benævnés Hovedet (Ceplia- lon), da det, foriiden Øinene, kxin bærer de 2 Par Følere og de egentlige Munddele (Over- og Under- læbe, Kindbakkerne og 2 Par Kjæver). Dets dorsale Parti, der er af betydelig større Udstrækning end dets ventrale, er fast forbundet med Rygskjoldet, a well defined oval area, in which are observed a number of lucid spots corresponding to the indivi- dual bundles of the adductor-muscle (see fig. 1, ms). A true cardinal margin, such as appears in the Ostracods and some Phyllopods (E-stheria, Limneti^), does not, however, exist, as the 2 valves pass dor- sally, imperceptibly into each other by an even curvature. Viewed laterally (PI. I, fig. 1) the cara- pace has a somewhat irregular oval or almost rhomboid form, having nearly the same height in front as behind. The dorsal margin is quite gently curved, and forms with the obliquely truncated posterior margins a very obtuse angle. The mobile frontal plate issues anteriorly from the upper part of the carapace, and in this situation appears as an acuminate, somewhat downwards-bent rostrum. Between it and the foremost somewhat bulging edges of the carapace, there is a narrow incision from which the eyes project. The lower edges are in their foremost portion greatly curved, but further back almost straight, and unite with a strong curve to the posterior edges, whereby is formed on each side a rounded lateral lobe that almost extends to the extrem- ity of the 4th segment of the posterior division of the body. Viewed from aljove (fig. 2) the carapace ap- pears very narrow and diminishing more rapidh- in front than liehind, where occurs a deep median, sinus narrowly rounded at the bottom, which sepa- rates the 2 lateral lobes from each other. At the foremost extremitj'- of the carapace appears the fron- tal plate, which now exhibits a narrow linguiform shape with the extremity evenly rounded (see also PI. II fig. 2). It is connected to the carapace by a distinct articulation, so that it can by means of special muscles be directed, now straight forward now bent in towards the anterior margin, in which case it, like a lid, covers in front the entrance to the cavity of the carapace. The carapace is per- fectly smooth, without any distinctly marked sculp- ture, and is devoid of bristles or spines; of rather tliin, flexible, chitinous consistency and semi-trans- parent, so that the enclosed body with its appen- dages may be observed through it. In order to closel3^ investigate the last-named, it becomes desirable to remove the one of the valves of the carapace (see PI. II fig. 1); it then appears, that tlie body throughout its entire length is dis- tinctly segmented, and that the segments group themselves into well defined sections of the Iiody. We are able to distinguish in all 4 such sections, of which 2 pertain to tlie anterior division, and tlie other 2 to the posterior division of the body. The front section of the anterior division of the body may be suitably termed the head (cephalon), as it, besides the eyes, only bears the 2 pairs of antennæ and the oral parts proper (anterior and posterior lips, the mandibles and 2 pairs of maxillæ). Its 12 som her danner den uniiddelbare Kropsvæg. Det følgende Afsnit, der forestiller livad man ialminde- lighed pleier at kalde «Truncus» eller «Thorax», men som maaske mere passende bør kaldes Midtkroppen (mesosome), bestaar af 8, i sin hele Omkreds tyde- ligt sondrede, og ensformigt udviklede Segmenter, der hvert bærer et Par Branchialfodder. Omvendt hvad Tilfældet er med Hovedet, har dette Afsnit sin største Udstrækning ventralt, idet begge Afsnit forbinder sig med hinanden langs en meget skraat gaaende Linie. Maalt langs Dorsalsiden er det her omhandlede Afsnit derfor neppe længere end Hove- det, medens det ventralt er næsten dobbelt saa langt. Bagtil forbinder det sig med Bagkroppen, uden at være afsat fra samme ved nogen mærkbar Indknibning. Det forreste Afsnit af Bagkroppen («Præabdomen», metasome) er sammensat af 4 Seg- menter, alle betydelig storre end de til Truncus horende Segmenter, og hvert forsynet med et Par kraftigt udviklede Svøramefodder. Det sidste af disse Segmenter har tydelige pladeformige Epimerer, der ender bagtil med et retvinklet Hjørne. Hele Bagkanten af dette Segment er desuden regelmæs- sigt sagtakke t, og ogsaa paa det foregaaende Seg- ment bemærkes i den dorsale Del en lignende, skjondt mindre udpræget Bevæbning af Bagkanten. Afsnit- tet, der successivt afsmalnes bagtil, dækkes til Si- derne næsten fuldstændigt a,f Hygskjoldet, medens dets dorsale Del træder mere eller mindre frit frem indenfor den dybe Indbugtning i Rygskjoldets bagre Del (se Tab. I, Fig. 2). Augaaende Længden af dette Afsnit, saa er den noget forskjellig hos de 2 Kjøn. Hos Hunnen er det, ialfald maalt langs Ventralsiden, neppe længere end Truncus, medens det selv hos endnu ikke fuldt udviklede Hanner (se Tab. II, Fig. 1) al tid er betydelig storre, i Overens- stemmelse med den kraftigere Udvikling af Svømme- fødderne. Det ydre, meget bevægelige Afsnit af Bagkroppen («Postabdomen , urosome), der gaar i Flugt med det forreste') og jævnt og hurtigt af- smalnes bagtil (se Tab. I, Fig. 1 og 2), bestaar lige- ledes af 4 Segmenter, hvoraf de 2 forreste er for- S3'nede med rudimentære Buglemmer, medens de 2 l^agerste ganske mangler saadanne. Det er af trind Form, næsten dobbelt saa langt som det forreste Afsnit og har Bagkanten af de 3 forre.ste Segmenter regelmæssigt sagtakket, ligesom paa de bagre Seg- menter af hint. Til Enden af sidste Segment er Halegrenene indleddede; de synes at svare til den saakaldte Furca hos Copepoderne og tør saaledes nærmest være at betragte som et i 2 Dele kløvet Endcsegment. Under Basis af Halegrenene gaar sidste Segment ud i 2, ved et smalt mediant Indsnit ') Hos Sl. Purimehcdia fi- dette Afsnit skarjit afsat fra Præ- abdomen. dorsal portion, which is of considerably greater extent than the ventral one, is firmlj' connected to the carapace, which here forms the immediate wall of the hoAj. The succeeding section, which represents what is usually termed the «truncixs» or «thorax», btit which might perhaps be more properly termed the middle section of the body (mesosome) consists of 8 tiniformly developed segments, di- stinctly separated throughout their entire circum- ference, each of which carries a pair of branchial legs. This section, conti-ary to what is the ease with the head, has its greatest extent ventrally, as both sections are connected to each other along a very oblique line of union. Measured along the dorsal side, the section referred to here is, therefore scarcely any longer than the head, while the ven- tral part is almost twice as long. Posteriorly it connects to the posterior division of the body without being demarcated from it by any notewor- thy constriction. The front section of the posterior division of the body («præabdomen», metasome) is composed of 4 segments, all considerably larger than the segments pertaining to the truncus, and each furnished with a pair of powerfully developed swimming legs. The last of tliose segments has di- stinct lamelliform epimeræ that terminate behind in a right-angled corner. The entire posterior mar- gin of this segment is, further, regularly serrated, and also in the preceding segment there is observed, on the dorsal part, a similar although not so distinct armature of the posterior margin. The section, which diminishes gradually backwards, is almost comple- tely covered at the sides by the carapace, while the dorsal part appears more or less uncovered inside the deep sinus in the posterior part of the carapace (see PI. I tig. 2). Regarding the length of this sec- tion, it is somewhat different in the 2 sexes. In the female it is, at any rate when measured along the ventral side, scarcely longer than the truncus, while it, in even not yet fully developed males (see PI. II fig. 1), is always considerably larger, in corre- spondence with the more powerful development of the swimming legs. The outer, very mobile section of the posterior division of the body («postabdomen», nrosome) which forms the immediate continuation of the anterior one ') and diminishes evenly and ra- \M\y backwards (see PI. I figs, 1 and 2) consists also of 2 segments, of which the 2 foremost ones are furnished with rudimentary ventral apjjendages, while the 2 hindmost ones are quite devoid of such appendages. It is cylindrical in form, almost twice as long as the foremo.st section, and has tlie po- sterior edge of the 3 foremost segments regularly ') 111 the gen. Paranehaiia this section is sharply tlellnod from the præabdomen. 13 skilte, tilspidsede Plader, der delvis dækker Anal- aabningen nedentil (se Tab. III, Fig. 12). Øinene (Tab. II, Fig. 1 og 7, 0, Fig. 3 og 4), der er fæstede temmelig nær sammen ved den forreste Ende af Hovedet, lige under Pandepladens Basis, er vel iidviklede og omtrent af Pandepladens halve Længde. De er tydeligt stilkede og meget frit be- vægelige, saa at de snart kan rettes ud til hver Side, snart lægges tæt ind mod hinanden og boies nedad, i hvilket Tilfælde de ganske skjules mellem den forreste Del af Rygskjoldets Valvler. Af Form er de noget sammentrykte, aflangt ovale, eller næ- sten halvmaanedaunede, med den ydre Del noget udvidet og skjævt afrundet, endende nedentil i et vinkelformigt Hjorne. Forkanten af Øiet er ganske glat, uden Spor af de stærke Sagtakker, som findes her hos Sl. ParanehaUa. Øiepigmentet, der hos det levende Dyr er af en vakker purpurrød Farve, fyl- der næsten ganske den ydre Halvpart af Øiet, og fra det iidstraaler til alle Kanter talrige Synsele- menter, i Form af smaa stærkt lysbi'vdende Legemer (Krystalkegler) af kort pæredannet Form. Derimod mangler den Øiet omgivende Hud (Cornea) ganske ethvert Spor af nogen egentlig Facettering som hos de høiere Crustaceer. Hvert Oie dækkes ved Roden af en fra Pandedelen udspringende skjælformig, i en skarp Spids udgaaende Plade, der næsten rækker til iVIidten af Øiets Længde (se Fig. .3, 4). De øvre Folere (Tab. II, Fig. 1, a', Fig. .5), der iidspringer lige under Øinene, er af kraftig, næsten fodformig Bygning og, lige udstrakte, omtrent af af Forkroppens Længde. Man kan paa dem adskille et tykkere, dobbelt vinkelboiet Skaft og 2 terminale Vedhæng af ulige Form, hvoraf det ene har Ud- seendet af en skjælformig Plade, det andet af en forlænget, mangeleddet Svobe. Skaftet bestaar af 4 Segmenter, hvoraf de 2 yderste er fast forbundne med hinanden, medens det foregaaende (2det) Led har en meget bevægelig Articulation saavel med Iste som 3die Led. Iste Led af Skaftet er, som det synes meget fast forbundet med Hovedet og kun lidet bevægeligt, hvorfor det ved Dissection vanske- ligt kan erholdes i Forbindelse med den ovrige Del. Det er (se Fig. 1, Fig. 7 a') af oval Form, uden en- hver Borstevæbning og opf3ddt med stærke Muskel- serrated, as in the posterior segments of the former. The caudal rami are articulated to the extremity of the last segment; they appear to correspond to the so-called furca of the Copepods, and may, therefore, be most properly considered to be a bifurcated terminal segment. Below the ba.ge of the caudal rami the last segment projects into 2, by a narrow median incision, separated acuminate lamellæ which partly cover the anal aperture beneath (see PI. Ill fig. 12). The eyes (PL II, fig. 1 and 7, 0, figs. 3 and 4), which are secured pretty closely together at the foremost extremity of the head, just below the base of the frontal plate, are well developed and about half the length of the frontal plate. They are distinctly stalked and very freely mobile, so that they may be directed, now to each side now laid close in to each other and bent downwards, in which case they become quite concealed between the foremost part of the valves cf the carapace. In form they are somewhat compressed, oblongo- oval, or almost semi-lunar, with the oiiter part somewhat expanded and obliquely rounded, ter- minating below in an angular corner. The anterior edge of the eye is perfectly smooth without trace of the powerful sawteeth found in the gen. Paraiiehalia. The ocular pigment, which, in the liv- ing animal, has a beautiful purple-red colour, occu- pies almost completely the outer half of the eye, and from it radiate numerous visual elements in all directions, in the form of small, .strongly re- fractive bodies (crj'stal cones) of short pyriform shape. On the other hand the enclosing integument (cornea) of the eye is quite deficient in every trace of any real facets such as exist in the higher Cru- staceans. Each eye is covered at the base by a squamiform plate that issues from the frontal part, and terminates in a sharp point which reaches nearly to the middle of the length of the eye (see figs. 3, 4). The superior antennæ, (Pl. II, fig. 1 a', fig. 5), which issue just under the ej^es, are of powerful, almost pediform structure, and when straightly extended are about same length as the anterior division of the body. "We can in them distinguish a thickish doubly geniculated peduncle and 2 terminal appen- dages of dissimilar form, of which the one has the appearance of a S([uamiform plate, the other of a pro. longed multi-articulate flagellum. The peduncle con- sists of 4 segments, of which the two outermost ones are firmly attached to each other, while the preceding joint (2nd) has a very flexible articulation both with the 1st and 3rd joints. The 1st joint of the peduncle is, apparently, very firmly connected to the head and but little flexible, hence it can with difficulty be obtained on dissection, in union with the remaining part. It is oval in form (see fig. 1, 14 knipper, der tjener til at bevæge den øvrige frie Del af Føleren. 2det Led, der ialmindeliglied er rettet lige fortil. dannende med Iste en mere eller mindre tydeligt udpræget alkiformig Boining, er omtrent saa langt som de 2 følgende tilsammen og noget forstykket paa Midten, næsten tendannet. Det bærer i Midten af den ovre Kant en enkelt stærk Fjærborste og i den nedre Kant, nærmere Enden, en Rad af omkring 8 saadanne, der hurtigt aftager i Længde nåaå; ved Spidsen af Leddet findes des- uden et Knippe af divergerende simple Børster. 3die Led, der sædvanlig med det foregaaende danner en meget stærk, retvinkJet knæformig Bøining, er noget indknebet ved Basis, men ndvides successivt mod Enden, der er skjævt afskaaret i Retningen forfra bagtil. Det kar i hver Kant, nær Enden, en Rad d-t oilierede Børster, bvoraf de i Bagkanten er længst. -tde Led er meget kort og bredt, næsten triangulært vjg ligesoni foregaaende skjævt afskaaret i Enden, men i modsat Retning, hvorved dets Bagkant bliver meget kort. Forkanten er bevæbnet med en Rad af korte Torner og ender med et noget sammentrykt, kort triangulært Fremspring, der ved Spidsen bærer en noget større Torn'). At de 2 terminale Vedhæng har det forreste Formen af en oval Plade, omtrent af samme Længde som Skaftets 3die Led, og langs Yderkanten og Spidsen tæt besat med fine haar- foi'mige Børster ordnede i to Rader. Det bagre Vedhæng, der repræsenterer den egentlige Svøbe, er omtrent af Skaftets Længde og afsmalnes successivt mod Enden. Den bestaar af omtrent 15 Led, hvoraf dog de 3 første ikke er tydeligt sondrede fra hin- anden. Hvert Led bærer ved Enden i Forkanten et Knippe af smaa Bør.ster, hvoraf nogle har Charac- teren af Sandsevedhæng (Lugtepapiller), og i Bag- kanten en enkelt simpel Børste. Hos den endnu ikke slægtsmodent ndviklede Han (Fig. 1) ligner disse Feiere temmelig samme hos Hunnen, alene med den Forskjel, at Svøben er mere opsvulmet ved Basis og delt i et noget storre Antal Led. De nedre Følere (Fig. 1, a-, Fig. (i), som ud- springer tæt bag de øvre, mangler ganske det blad- formige Vedhæng, men er forøvrigt hyggede efter samme Type som hine og har ligeledes Skaftet dob- belt geniculeret. Iste Led er, som paa de evre, meget fast forbundet med Hovedet, stærkt museulost fig. 7, a'), without trace of any setaceous armature, and filled with strong muscular bundles, which serve to move the remaining free part of the antenna. The 2nd joint — which is usually directed straight forward, forming with the 1st a more or less dis- tinctly marked elbow-shaped bend — is about as long as the 2 succeeding ones together and some- what tumefied at the middle, almost fusiform. It carries in the middle of the upper edge a single strong, plumose bristle, and on the lower edge, nearer the extremity, a series of about 8 similar bristles that rapidly diminish in length outwards: at the tip of the joint there is, further, observed a bundle of divergent simple bristles. The 3rd joint, which with the preceding one usually forms a verj'- ■ strong right-angled geniculate bend, is somewhat con- stricted at the base but gradually ex])ands towards the extremity, which is obliquely truncated in a direc- tion from before backwards. It has on each edge, near the extremity, a series of ciliated bristles, of which those on the posterior edge are the longest. The 4th joint is very short and broad, almost triangular, and like the preceding one obli([uely truncated at the extremity but in the opposite direction, causing its posterior edge to be very short. The anterior edge is armed with a series of short spines and termin- nates in a somewhat compressed short triangular prominence, which at the point carries a somewhat largish spine ') Of the two terminal appendages the foremost one has the form of an oval lamella, about the same length as the 3rd joint of the pe- duncle, and along the outer edge and at the point it is closely beset with delicate cajjilliform bristles arranged in two series, Tlie postei'ior appendage, which represents the flagellum proper, is about same length as the peduncle and tapers gradually towards the extremity. It consists of about 15 joints, of which, however, the 3 first ones are not distinctly separated from each other. Lach joint carries at the extremity, on the anterior margin, a bundle of small bristles, of which some have the nature of sensory appendages (olfactory papillæ), and on the posterior edge a single simple bristle. In the still incompletely sexually developed male (fig. 1) these antennæ resemble pretty much those of the female, with the sole diiference, that the flagellum is more tumefied at the base and divided into a somewhat larger number of joints. The inferior antennæ (fig. 1 a''', fig. (!) whicli issue close behind the superior ones, are completely without the foliaceous appendage, but are constructed, other- wise, according to the same ty]ie as those, and have also the peduncle doubly geniculated. The 1st joint is, as in the superior ones, very firmly united to ') Hos Sl. Panmebalia er dette Fremspring betydelig større og grovt sagtakket i Forkanten. ') In the gen. Paraiicbalia, this prominence is considerably larger and coarsely serrated on the anterior edge. 15 og uden ftnhver Borstebevæbning. 2det Led, der omtrent er af samme Størrelse som Iste, mangler ligeledes Børster, men gaar fortil ud i et kort tand- formigt Fremspring. Den ydre Del af Skaftet dan- ner ogsaa lier en stærk knæformig Beining med fore- gaaende Led, men bestaar kun af et enkelt Led, paa livilket dog en oprindelig Tvedeling er antydet ved en skarpt markeret Afsats baade fortil og bagtil '). Til den bagre Afsats er fæstet en stærk Fjærborste, og langs Forkanten af Leddet fiudes en hel Del saa- danne Børster, tildels af betydelig Længde. navnlig ved Enden, hvor de delvis er krandsformigt stillede omkring Leddet. Desuden tindes langs den ovre Halvpart af Forkanten en Rad af Smaatorner, der nedad snccessivt tiltager i Længde, og en Del lig- nende Torner bemærkes ogsaa ved Enden af Leddet fortil mellem Børsterne. Svoben er betydelig (næ- sten dobbelt) længere end paa de øvre Følere og bestaar af omkring 20 børstebesatte Led, hvoraf dog de i) eller 4 inderste er mindre tydeligt begrændsede. Hos den endnn ikke slægtsmodent udviklede Han skiller disse Følere (Fig. 1, a^) sig væsentlig kun derved, at Svøben er meget tæt ringet, eller delt i et stort Antal, endnu ufuldstændigt begræ.ndsede Led. Overlæben (Fig. 7. L. Fig. 8), der til Siderne ganske dækkes af de nedre Foleres Basalled, danner et t\"deligt convext Fremspring af afrundet Form og med den bagre Kant svagt indlragtet i Midten samt her besat med fine Haar. Underlæben (Fig. 7, 1, Fig. 9) er meget liden og vanskelig at isolere. Den har imidlertid fore- kommet mig at frembyde det Fig. ',• fremstillede Udseende af en i Midten dybt indskaaret og delvis cilieret Plade. Kindbakkerne (Fig. 1, M, Fig. 10) har et for- holdsvis meget lidet Corpus, hvis ydre Del er baad- formig og ender opad i en Spids, hvormed det arti- culerer til Rvgskjoldets indre Flade. Dets indre Hule er fyldt med de stærke, i Midten ved en chitin- agtig Sene forbundne Adductormuskler (se Fig. 10), og fra den bagre Kant udgaar en tynd Cbitinsene, hvortil Kindbakkernes Rotationsmuskler fæster sig. Den næsten under en ret Vinkel med det øvrige Corpus indboiede Tyggedel er (se Fig. 11) i Enden delt i 2 G-rene, hvoraf den ydre har Formen af en liden triangulær Lamelle, der svarer til det tandede . Parti (cutting edge) hos andre ("rustaceer, medens the head, strongly musculous, and without any ar- mature of bristles. The 2nd joint, which is about the same size as the 1st one, is also quite deficient in bristles, but passes, in front, into a short denti- form projection. The outer part of the peduncle also forms here a strongly geniculated bend with the preceding joint, but consists of only a single joint, upon which, however, there is an indication of an original subdivision in the shape of a sharply defined ledge both in front and behind '). Attached to the posterior ledge there is a powerful plu- mose bristle, and along the anterior edge of the joint quite a number of such bristles may be observed, partly of considerable length, especially at the ex- tremity, whei'e they are partly arranged in a ver- ticillate manner around the joint. Further, there may be observed along the upper half of the an- terior edge a series of small spines, which gradu- ally increase in length below; and a number of similiar spines are also observed at the extremity of the joint in front, between the bristles. The fla- gellum is considerably longer (nearly double) than on the superior antemiæ, and consists of about 20 joints beset with bristles, of which, however, the 3 or 4 innermost ones are less distinctly defined. Li the not yet sexually fully developed male these antennæ distinguish themselves chiefly (fig. 1, a^), onh^ by the circumstance that the flagellum is very closely annulated, or divided into a large number of still imperfectl}' defined joints. The anterior lip (fig. 7 L, fig. 8) which, at the. sides, is quite covered by the basal joints of the inferior antennæ, forms a distinctly convex promi- nence of rounded form, with the posterior margin faintlj^ hollowed in the middle and beset here witii delicate hairs. The posterior lip (fig. 7 1, fig. 9) is very small and difficult to isolate. It appears, however, to me, to present the appearance of a partly ciliate lamella, deeply incised in the middle, as shown in fig. 9. The mandibles (fig. 1, M, fig. 10) have, relati- vely, a very small corpus, whose outer portion is navicular in form and terminates above in a jooint, by which it articulates with the inner surface of the carapace. Its inner cavity is occupied by the pow- erful adductor muscles, which are connected in the middle by a chitinous tendon (see fig. 10), and from the posterior margin a thin chitinous tendon issues, to wliich the rotatory muscles of the mandibles are attached. The masticatory part, which is bent inwards almost at a right angle to the remaining corpus (see fig 11), is divided at the extremity into 2 rami, of which the outer has the form of a ') Hos Sl. XebaJiopm^ best.iar denne I>el .if '2 tydeligt l>e- gi'fendsede Led. ') In the fien. Xeh({!inj)sis this part cnnsits of 2 distinctly detiued joints. 16 den indre og betydelig større Gren svarer til Molar- processen. Den første er ganske simpel og har kun strax indenfor Spidsen et yderst lidet tandformigt Fremspring. Den sidste er af cylindi'isk Form, lidt buet, og har som sædvanlig Enden iint riflet samt mere tvært afkuttet paa hoire end paa venstre Kindbakke. Palpen (Fig. 1,7, Mp, Fig. 10), der ud- gaar fra Corpus noget fortil paa det Sted, hvor Tj-ggedelen forbinder sig med den ydre, baadformige Del, er af særdeles betydelig Størrelse, næsten 3 Gange saa lang som selve Corpus, og viser en Byg- ning idethele overensstemmende med samme hos høiere Crustaceer, navnlig Amphipoderne. Den be- staar af 3 skarpt begrændsede Segmenter eller Led, alle omtrent af ens Størrelse, eller kun ganske lidt tiltagende i Længde iidad. Iste Led er simpelt cylin- driskt, dog noget fortykket i hver Ende, og mangler ganske Børster. Det forbinder sig med 2det Led paa en ganske egen Maade, saa at begge med hin- anden danner et Slags Knæ. 2det Led er i sit ba- sale Parti noget opsvulmet og danner umiddelbart indenfor Ledfoiningen med Iste, en albuformig Ud- vidning. Det afsmalnes suecessivt mod Enden og har i Midten af Yderkanten 3 — 5 tynde Borster. Sidste Led, der er meget bevægeligt forbundet med 2det, er temmelig smalt, stærkt sammentrykt fra Siderne og ganske lidt bredere i sit ydre Parti, som er jevnt tilrundet i Enden. Det bærer langs den nedadvendte skarpe Kant en tæt Rad af fint cili- erede, toleddede Børster og har desuden ved Spid- sen nok en Rad af meget fine og stærkt krummede Børster. Leddets øvre Kant mangler Børster, men viser i sit bagre Parti en særdeles fin Ciliering. I sin normale Situs convergerer de to Palper stærkt ved Basis (se Fig. 10), saa at 2det Led paa begge kommer til at ligge tæt sammen i Juxtaposition, indenfor Basalleddene af de 2 Par Folere. Sidste Led paa hver divergerer igjen noget og træder frit frem enten foran eller mellem Følernes Rod (se Fig. 1, Mp). Iste Par Kjæver (Tab. II, Fig. 1 & III, Fig. 1) er af af rundet Form og gaar indad ud i to korte, stumpt afrundede Tyggelappe, hvoraf den ydre er størst, næsten af øxedannet Form og, foruden med nogle tildels cilierede Børster, bevæbnet i sit bagre Parti med en Gruppe af smaa, i Enden tve- delte Torner (Fig. 1 a). Den indre Tyggelap er for- holdsvis liden, af membranøs Beskaffenhed og paa den næsten tvært afkuttede Ende forsynet med en tæt Rad af san-deles fine cilierede Børster, foruden en Del korte Torner. Fra Enden af disse Kjæver small triangular lamella, which corresponds to the denticular portion (cutting edge) in other Crusta- ceans; while the inner, considerably larger ramus corresponds to the molar expansion. The first-named is quite simple, and has, immediately inside the point, only an extremely small dentiform prominence. The last-named is cylindrical in form, slightly curved, and, as usual, has the extremity finely fluted and more obtxisely truncated on the right than on the left mandible. The palp, (fig. 1, 7, Mp. fig. 10), which is.sues from the corpus a little in advance of the place where the masticatory part is con- nected to the outer navicular part, is of parti- cularly large size, almost 3 times as long as the corpus itself, and exhibits a structure corresponding, upon the whole, with that of the higher Crustaceans, especially the Amphipods. It consists of 3 sharply defined segments or joints, all of about the same size, or only qi;ite slightly increasing in length out- wards. The 1st joint is simple cylindric in form but somewhat tumefied at each extremity, and is quite devoid of bristles. It is connected to the 2nd joint in quite a peculiar manner, so that they form with each other a kind of knee. The 2nd joint is some- what tumefied in its basal part, and foi'ms imme- diately inside the articulation to the 1st joint an elbow-shaped expansion. It diminishes gradually towards the extremity, and has 4 — 5 slender brist- les on the middle of the outer margin. The ter- minal joint, which is verj' flexibly connected to the 2nd one, is pretty narrow, strongly comjn'essed from the sides and quite slightly broader in its outer part, which is evenly rounded at the extremity. It bears along the downward Itent sharp margin a close series of delicate double-jointed bristles, and has, further, at the point, yet another series of very delicate and strongly bent bristles. The upper mar- gin of the joint has no bristles, but exhibits a parti- cularljr delicate ciliation in its posterior part. In its normal situs the 2 palpi converge strongly at the base (see fig. 10), so that the 2nd joint of each lies in close juxtaposition inside the basal joints of the 2 pairs of antennæ. The terminal joint of each diverges again a little, and appears freely forward either in front of or between the bases of the antennæ (see fig. 1, Mp). The 1st pair of maxillæ (Pl. II, figs 1 and 7. m'; Pl. III, fig. 1) are rounded in form and pass over, inwards, into two short, obtusely rounded mastica- tory lobes, of which the outer one is the largest, almost securiform, and armed, besides with some partly ciliate bristles, also, in its posterior part, with a gro\ip of minute spines bifurcated at the ex- tremity (fig. 1 a). Tlie inner masticatory lobe is relatively small, of menil)ranous nature, and fur- nished on the almost obtusely truncated extremity with a close series of delicate ciliate bristles besides 17 iidgaar et besynderligt, stærkt forlænget Vedhæiig (Tab. Ill, Fig. 1, p), som ifolge sit Udspring aabeii- bart repræsenterer en eiendommeligt modifieeret Palpe. Den bestaar af en noget tykkere, med en Del tynde Muskelbundter fyldt Basaldel, og en tynd Endesnært, som dog begge gaar ganske umærkeligt over i hinanden. Basaldelen, der paa 2 forskjellige Steder har et Bundt af tynde divergerende Borster, viser strax ved sit Udspring en abrupt dobbelt vinkelformig Bøining udåd og bagtil, hvorfor den tynde, næsten borsteformige Endedel bliver rettet skråa t bagtil og opad langs Siderne af Truncus, rækkende med sin Spids lige op til dennes dorsale Flade (se Tab. II, Fig. 1, m'). Langs den ene Kant af denne Endedel er med korte Mellemrum fæstet circa 16 laiige og t3-nde, ucilierede Borster og til Spidsen 3 lignende ; alle Børster viser i Enden en eiendommelig, næsten korketrækkerformig Krumning og er temmelig stive, samt vende ialmindelighed nedad og indad. Angaaende dette eiendommelige Vedhængs Function, er der ingen Tvivl om, at det tjener til at rense Rygskjoldets Hule, og dermed ogsaa de tandre Branchialfodder, for fremmede i den indtrængende Dele, i Lighed med hvad Tilfældet er med det bagre Fodpar hos visse Ostracoder (Cypri- dinider, Cj'prider). 2det Par Kjæver (Tab. II, Fig. 1 og 7, m'^ Tab. III, Fig. 2) er ndpræget pladeformige og af temme- lig compliceret Bygning, mest mindende om samme hos de hoiere Crustaceer (Podophthalmia). Man kan paa dem adskille en af 2 utydeligt begrændsede Segmenter bestaaende Basaldel og 2 fra denne fortil udgaaende Grene. Basaldelen har indad 4 borste- besatte Lappe, der utvivlsomt svarer til Tyggelap- pene paa Iste Par, med den Forskjel, at hver Tygge- lap her altsaa er dobbelt eller delt i to. Den for- reste af disse 4 Lappe er imidlertid meget liden, knudeformig og bærer 6 lange, cilierede Borster. De 3 øvrige Lappe er ligeledes børstebesatte paa den tvært af kuttede Ende; men Børsterne er her meget kortere og tættere samt delvis ordnede i flere Ræk- ker. Den midterste af disse 3 egentlige Tyggelappe er betydelig smalere end de 2 ovrige, som omtrent indbyrdes er af ens Størrelse. Af de 2 Endegrene er den indre (p), der forestiller Endognathen eller Palpen, af betydelig Størrelse, noget afsmalnende mod Enden og delt i 2 vel begrændsede Led, hvoraf det Iste er størst. Begge Led er i Inderkanten be- satte med talrige cilierede Borster, delvis ordnede i 2 Rækker, og en af de fra Spidsen udgaaende ud- mærker sig ved betydelig Længde. Den ydre Grren (ex), eller Exognathen, er betydelig mindre end den indre og rækker neppe udover dennes Iste Led. Den har Formen af en meget smal elliptisk Plade, der langs hele Inderkanten og Spidsen er forsynet 3 — G. 0. Sårs: Fauna NorvegiA. a niimber of short spines. From the extremity of these maxillae a strange, greatly prolonged appen- dage issues (PI. Ill fig. 1, p.) which judged by its origin evidently represents a peculiarly modified palp. It consists of a somewhat thickish basal part occupied by a number of thin bundles of muscles, and a slender terminal lash which, however, pass imperceptiblj' the one into the other. The basal part, which in two different places has a bundle of slender divergent bristles, exhibits, immediately at its origin, an abrupt double-kneed bend outwards and back- wards, which caiTses the thin, almost setiform ter- minal part to become directed obliqiiely backwards, and upwards along the sides of the truncus reaching, with its point, qiiite up to its dorsal surface (see PI. II, fig. 1 m'). Along the one margin of this terminal part there are secured at short inter- vals, about 16 long, slender, non-ciliate bristles, and 3 of the same kind at the tip; all the brist- les exhibit at the extremity a peculiar, almost cork- screw-shaped bend and are rather stiff, and generally turn downwards and inwards Regarding the func- tion of this peculiar appendage, there is no doubt that it serves to clean the cavity of the carapace, and at same time the delicate branchial legs of foreign, to it penetrating, sub.stances, like what is the case with the posterior pair of legs in certain Ostracods (Cypridinids, Cyprids). The 2nd pair of maxiike (PI. II, fig. 1 and 7, m''; PI. Ill fig. 2) are of distinguished lamelliform sliape, and of rather complex structure, reminding one most of tiie same maxillæ in the higher crustaceans (Po- dopthalmia). We can in them distinguish a — of 2 indistinctly defined segments constructed — basal part, and two branches issuing from it in ft'ont. The basal part has, inwards, 4 lobes beset with bristles which indubitably correspond to the masti- catory lobes of the 1st pair, with this difierence, that each masticatory lobe is here double or bifur- cated. The foremost of these 4 lobes is, however, very small, nodiforra, and carries 6 long ciliated bristles. The 3 remaining lobes are also beset with bristles on the obtu.sely truncated extremity; but the bristles are here much shorter and closer and, also, partly arranged in several series. The mesial one of those 3 masticatory lobes proper is consider- ably narrower than the 2 others, which are mutu- ally of about the same size. Of the 2 terminal branches, the inner one (p) which represents, the endognath or the palp, is of considerable size, dimi- nishing somewhat towards the extremity, and divided into 2 well defined joints, of which the 1st one is the largest. Both joints are on the inner margin beset with numerous ciliated bristles, partly arranged in 2 series, and one of them issuing from the point distinguishes itself by its great length The outer branch (ex), or the exognath, is considerably smaller 18 med en regelmæssig Rad af temmelig lange, fint cilierede Randbørster. De 8 Par Branchialfodder, som umiddelbart følger after Kjæverne, er alle byggede efter samme Type og ligger tæt ind mod liinanden i Form af tværstillede Plader, noget mere convexe fortil end bagtil (se Tab. II, Fig. 1). De tiltager noget i Stør- relse indtil 4de Par og aftager saa igjen succes.sivt bagtil. Paa dem alle kan man (se Tab. III, Fig. 3 — 6) adskille 3 fra en fælles Ba.sis ndgaaende Ho- veddele, som vi, i Lighed med hvad man pleier hos andre Krebsdyr, kan beuævne : Endopodit (p), Exopodit (ex) og Epipodit (ep). Den fælles Basaldel bestaar, som paa 2det Par Kjæver, af 2 ufuldkom- ment sondrede Segmenter, der i Inderkanten har en dobbelt Rad af Børster, hvoraf de paa Iste Segment delvis udmærker sig ved betydelig Længde. Endo- poditen (p), der danner den umiddelbare Fortsættelse af Basaldelen, danner en mod Enden successivt af- smalnende Stamme, paa hvilken der er en svag An- tydning til Segmentering. Denne Del er hos den ægbærende Hun betj'delig stærkere forlænget end hos yngre Individer af begge Kjøn og har sidste Led vel sondret, noget ombøiet og besat med sær- deles lange divergerende Fjærbørster, der delvis rager frem nedenfor Rygskjoldets Valvler (se Tab. I, Fig. 1 ). Forovrigt er Endopoditen langs hele Inder- kanten besat med Børster, der fordetmeste er ord- nede i en dobbelt Rad og umiddelbart fortsætter de paa Basaldelen forekommende Børsterækker. Exo- poditen (ex), der er fæstet til Basaldelens 2det Segment, udenom Endopoditen, har Characteren af en bred, langs Midten med en noget fortykket Ribbe forsynet Plade, noget forskjellig i Form paa de forskjellige Branchialfodder. Paa Iste Par (Tab. III, Fig. 3) er den regelmæssig oval og i Yderkanten besat med en Rad af circa 18 tynde Børster, til- tagende i Længde mod Spidsen. Paa de følgende Par (Fig. 4, 5) bliver den successivt noget større og stærkere udvidet i Enden, som er skjævt afrundet og kun besat med faa og spredte Randborster. Paa sidste Par endelig (Fig. 6) har den antaget en tem- melig smal elliptisk Form. Eiiipoditen (ep), der ved en kort Stilk er fæstet til Ydersiden af Basaldelens Iste Segment, er af særdeles betydelig Størrelse, saa at den mere eller mindre fuldstændigt dækker de øvrige Dele, naar disse Lemmer sees in situ fra Ydersiden (se Tab. II, Fig. 1). Den har Formen af en elliptisk eller næsten halvmaanedannet Plade og gaar ud i en dorsal og en ventral Lap, adskilte i Midten ved en tværs over Epipoditen fra dennes Fæste loljeiide fortykket Ribbe. Ligesom Tilfældet var med Exopoditen, er der ogsaa nogen Forskjel i Epipoditens Størrelse og Form paa de forskjellige than the inner one and scarcely extends beyond its 1st joint. It has the form of a very narrow elli])- tieal lamella which, along the entire inner mar- gin and at the point, is furnished with a regular series of pretty long finely ciliated marginal bristles. The 8 pairs of branchial legs which immediately succeed the maxillæ, are all constructed on the same type, and lie close in. to each other in the form of transversally placed lamellæ, rather more convex in front than behind (see PI. II, fig. I). They increase somewhat in size as far as to the 4th ])air and then gradually diminish backwards. In all of them 3 chief portions issuing from a common base (see PI. Ill, figs. 3 — (j) may be distinguished, which we, like what we are accustomed to do with other crusta- ceans, may tei'm endopodite (p), exopodite (ex) and epipodite (ep). The common basal part consists, as in the 2nd pair of maxillæ, of 2 imperfectly .sepa- rated segments which have a double series of brist- les on the inner margin, of which those on the first segment are distinguished by their great length. The endopodite (p) which forms the immediate con- tinuation of the basal part forms a trunk, dimi- nishing gradually towards the extremity, upon which there is a faint indication of a segmentation. This part is, in the ovigerous female, considerably more prolonged them in young individuals of both sexes, and has the terminal joint well separated, s.omewhat recurvate and beset with particularly long divergent and plumose bristles, which partly project below the valves of the carapace (see PI. I, fig. 1). The endo- podite is, otherwise, beset with bristles along the entire inner margin, which are chiefly arranged in a double series, and are immediate continuations of the bristle series appearing on the basal part. The exopodite (ex), which is attached to the 2nd seg- ment of the basal part, outside the endopodite, has the character of a broad lamella, furnished along the middle with a somewhat thickened rib, and is a little different in form in the various branchial legs. In the 1st pair (PI. Ill, fig. 3) it is regularly oval and beset on the outer edge with a series of about 18 slender bristles increasing in length towards the point. In the succeeding pairs (figs. 4. 5) it becomes gradu- ally somewhat larger and more strongly expanded at the point, which is unevenly rounded and beset with only few and scattered marginal bristles. Fin- ally, in the last pair (fig. 6) it has assumed a pretty narrow ellipti(!al form. The epipodite (ep); which is attached by a short stem to the outer side of the 1st segment of the basal pai't, is of particularly large size, so that it more or less completely covers the remaining parts when those appendages are viewed in situ from the outer side (see PL II, fig. 1). It has the form of an elliptical, or almost semilunar plate, and passes out into a dorsal and a ventral lobe divided in the middle by a thickened rib which 19 Par Branchialfødder. Dens Størrelse tiltager noget indtir 4de Par, hvor den er størst, og aftager saa igjen successivt paa de bagenfor liggende Par (se Tab. II, Fig. 1). Paa Iste Par (Tab. III, Fig. 3) er dens ventrale Lap betydelig større end den dor- sale og smalt tilløbende i Enden, medens lun er jevnt afrnndet. Paa de følgende Par (Fig. 4, 5) bliver Forskjellen mellem de 2 Lappe efterhvert mindre, og paa sidste Par (Fig. 6) er Forholdet det omvendte af hvad det er paa Iste Par, idet den dor- sale Lap her er den største og mere smalt ndlobende end den ventrale. Saavel Exopoditen som Epipoditen, men især denne sidste, viser den for Grjelleelemen- terne hos andre Krebsdyr characteristiske spongiose Structnr, idet der mellem de 2 Lameller, hvoraf begge disse Vedhæng begrændses, findes et compli- ceret System af med hinanden anastonioserende Hul- rum, hvori der hos det levende Dyr foregaar en livlig Blodcirciilation. At begge disse Vedhæng der- for er af respiratorisk Betydning, er ganske utvivl- somt, skjondt, som senere skal vises, ogsaa selve R-ygskjoldet spiller i denne Henseende en vigtig Rolle. De 4 forreste Par Bagkropslemmer (se Tab. II, Fig. 1) er overordentlig kraftigt udviklede Svommeappa- rater, der i flere Henseender, og ogsaa i den Maade, hvorpaa de bevæges, minder om Copepodernes Svom- mefødder. De er alle hyggede efter samme Type og bestaar hvert (se Tab. III, Fig. 7 og D) af en med talrige stærke Mnskelbundter fyldt, noget affladet Basaldel, og to fra dennes Ende udgaaende, med cilierede Svømmebørster forsynede, enleddede Grene eller Aarer, hvoraf den ydre ialmindelighed er ret- tet .stærkt udåd og i Yderkanten bevæbnet med kraftige Torner. Paa alle Par findes ved Enden af Basaldelen paa den indre Side en eiendommelig indadrettet Fortsats (Fig. 8), der moder den tilsva- rende paa den anden Side og i Spidsen er bevæbnet med et Antal, sædvanlig 4, krogformige Torner (Fig. 8 a). Ved disse Torner hægtes de 2 til samme Par hørende Fødder ligesom sammen, saa at deres Bevægelser kun kan ske samtidigt. Iste Par Svomniefødder (Fig. 7) skiller sig kjen- deligt fra de ovrige, saavel ved Basaldelens Form og Bevæbning som ved Beskatfenheden af den ydre Gren. Basaldelen, der ligesom paa de ovrige Par har et ganske kort Rodled, er her forholdsvis læn- gere og smalere, noget aftagende i Brede mod En- den, og bevæbnet med 4 lange Torner, hvoraf en er crosses the epipodite froYii its ])oint of attachment. As was the case with the exopodite, there is also some difference in the size and form of tlie epipo- dite in the varions pairs of brancliial feet. The size increases somewhat until the 4th pair, where it is greatest, and it then diminishes again, sTiccessively, in the pairs situated behind (see PI. 11, fig. 1). In the 1st pair (PI. Ill, fig. 3) the ventral lobe is con- siderably greater than the dorsal one, and projects in a narrow pointed form at the extremity, while the latter is evenly rounded. In the succeeding pairs (figs. 4, 5) the difference between the two lobes becomes gradually less, and in the last pair (fig. 6) the relation is the reverse of what it was in the 1st pair; as the dorsal lobe is here the largest one and more narrowly projecting than the ventral one. Both the exopodite and thp epipodite, but especially the last-named, exhibit the characteristic spongy structure for the gill-elements in other Crustacea; as between the 2 lamellæ by which the appendages of both are limited, there is found a complicated system of cavities, anastomosing with each other, in which, in the living animal, an active blood cir- culation proceeds. That both these appendages are therefore of respiratory importance is perfectly indu- bitable, although, as will be subsequently shown, the carapace itself also plays an important part in that respect. The 4 foremost pairs of the posterior appen- dages of the body (see PI. II, fig. 1) are extremely powerfully developed swimming legs which, in several respects as well as in the manner in which they are moved, remind us of the swimming feet of the Copepods. They are all constructed on tlie same type, and consist, each (see PI. Ill, figs. 7 and P), of a somewhat flattened basal part filled with nu- merous strong bundles of muscles, and two branches or oars, issuing from its extremity' and furnished with ciliated swimming-bristles. Of these branches the outer one is usually directed strongly outwards, and is armed on the outer edge with powerful spines. In all the pairs there is found, at the extremity of the basal part on the inner side, a peculiar projec- tion directed inwards (fig. 8), which meets the corre- .sponding one of the other side, and is armed at the point with a number — usually 4 — uncinate spines (fig. 8 a). The 2 feet pertaining to the same pair are, as it were, hooked together b}' these spines, so that their movements can only take place simul- taneously. The 1st pair of swimming feet (fig. 7) are per- ceptibly distinguished from the others, both by the form and armature of the basal part as well as by the nature of the outer branch. The basal part which, as upon the other pairs, has a quite short basal joint, is here relatively longer and narrower, somewhat narrowing in breadth towards the extre- 20 fæstet helt oppe ved Basis til Yderkanten. en anden helt nede ved det ydre Hjorne, medens de 2 øvrige ndgaar fra den nederste Del af Inderkanten. Den ydre Gren er temmelig smal, men snccessivt noget iiredere mod Enden, og har langs Yderkanten en regelmæssig Rad af circa 20 korte Torner, hvorpaa følger, fæstet til en særegen Afsats, en betydelig stærkere saadan. Fra den noget skraat afkuttede Ende udgaar 3 stærke divergerende Torner, hvoraf den yderste er længst, den midterste kortest. Hele den indre Kant af Grenen er forøvrigt besat med en tæt Rad af lange og tynde cilierede Børster. Den indre Gren er betydelig længere og ogsaa sma- lere end den ydre, næsten lineær, og viser ved Basis et nfuldstændigt sondret lidet Rodled. Den er i begge Kanter for.synet med en Rad af lignende Svommebørster som paa den ydre Gren og gaar ved Enden ud i en kort dolkformig Spids, indenfor hvil- ken en lang bagi;drettet Torn er fæstet. Paa de øvrige Svømmefodder (Fig. 9) er Basal- delen kortere og bredere, mere affladet, og har Yder- kanten tilskjærpet samt endende nedad med et spidst udtrukket Hjorne. Inderkanten er ligesom Y"der- kanten ixden Torner, men har 2 Knipper af meget fine Børster, skilte ved et længere Mellemrum. Mel- lem de 2 Grene danner Basaldelen et lancetformigt tilspidset Fremspring. Den jalre Gren er forholds- vis storre og bredere end paa Iste Par og har langs Y^derkanten 7 Afsatser, hver bevæbnet med 2 tæt sammenstillede divergerende Torner; fra Spidsen ud- gaar, som paa Iste Par, 3 Torner, som her succes- sivt tiltager i Længde indad. Den indre Gren er kun lidet længere end den ydre, men betydelig sma- lere, forovrigt af samme Beskaftenhed som ]iaa Iste Par. Det bagerste Par skiller sig neppe fra de • 2 foregaaende uden derved, at det er noget mindre. De 2 Par rudimentære Bagkropslemmer, der er fæstede til Bugsiden ved Enden af 5te og 6te Seg- ment (se Tab. I, Fig. 1), er begge af meget enkel Bygning og som det synes ganske ubevægelige. Iste Par (Tab. III, Fig. 10) er det største og be- staar hvert af 2 Segmenter, et kort Basalled og et mere langstrakt, i sin ydre Del lidt udvidet Ende- led. Dette sidste er langs Inderkanten besat med fine Børster og har langs den skraat afskaarne Ende- rand en Rad af 7 Torner, hvoraf den yderste er længst; mellem Tornerne bemærkes ogsaa en Del fine lige udåd rettede Børster. — 2det Par (Fig. 11) er neppe mere end lialvt saa lange som Iste og be- staar hvert af et enkelt ovalt Led, hvis Inderkant er ret, medens Yderkanten er noget buet. Til den mity, and armed with 4 long spines, of which one is secured to the outer edge, quite up at the base; another quite down at the outer corner, whilst the 2 others issue from the lowest part of the inner edge. The outer branch is pretty narrow, but is somewhat more successively broad towards the ex- tremity, and has a regular series of about 20 short spines along the outer edge, succeeded by a consi- derably more powerful one secured to a special pro- jection. From the somewhat obliquely truncated extremity there issue, 3 strongly divergent spines, of which the outermost one is the longest, and the medial one shortest. The entire inner edge of the branch is otherwise beset with a close series of long and slender ciliated liristles. The inner branch is con- siderably longer and also narrower than the outer one, almost linear, and exhibits at the base an imperfectly separated, small basal joint. It is fur- nished on both edges with a series of similar swim- ming bristles as on the outer branch, and at its extremity passes into a short lanceolate point, inside of which a long spine, directed backwards, is secured. On the other swimming feet (fig. 9) the basal jiart is shorter and broader, more flattened, and has the outer edge sharpened and terminating down- wards in an acutely drawn out corner. The inner edge, like the outer one, is devoid of spines, but has two bundles of very fine bristles, separated by a longish interval. Between the two branches the basal part forms a lanceolate pointed projection. The outer branch is relatively larger and broader than in the ]st pair, and has 7 projections along the outer edge, each of which is armed with 2 diver- gent spines placed closely to each other; from the point there issue, as in the 1st pair, 3 spines, which increase here successively in length inwards. The inner branch is only a little longer than the outer one, b\;t considerably narrower; otherwise of the same character as in the 1st pair. The last pair are scarcely distinguished from the 2 preceding ones, unless in that they are somewhat smaller. The 2 pairs of rudimentary, posterior append- ages of the body, which are secured to the ventral side at the extremity of the oth and 6th segments (see PI. I, fig. 1), are both of very simple structure, and, as it appears, quite immobile. The 1st pair (PI. Ill, fig. 10) are the largest, and each consists of 2 seg- ments, a short basal joint and a more elongated, in its outer part slightlj' widened, terminal joint. This last is beset along the inner edge with fine spines, and along the obliquely truncated terminal margin has a series of 7 spines, of which the outermost one is the longest; between the spines there are observed, also, a number of fine bristles directed straight outwards. The 2nd pair (fig. 11) are scarcely more than half as long as the 1st, and each consist of a 21 sidste er fæstet 4 stærke Tomer, og fra Spidsen udgaar 2 lignende, livoraf den inderste er længst. Imellem Tornerne findes ogsaa her fine udadrettede Borster, medens Barsterne i Inderkanten er stærkt rediicerede. Halegrenene (Fig. 12) er omtrent saa lange som de 2 sidste Bagkropssegmenter tilsammen og ialmin- deliglied stærkt divergerende. De er af smal lineær Form, ganske lidt afsmalnende mod Enden og rundtom fors_ynede med en Rad af korte ucilierede Torner, der ved Spidsen antager Formen af stærkt forlængede Borster. Foniden disse findes langs Jnderkanten en Rad af betydelig længere og finere, tæt cilierede Borster. Dyrets Farve er noget varierende fra meget bleg gulagtig til temmelig intens rodbnin. De mest udpræget farvede Exemplarer har jeg observeret i vor arktiske Region. • Beskrivelse af «len slægtsinodue Han. Medens den endnu ikke slægtsmodne, skjondt forøvrigt fuldt iidvoxede Han (se Tab. II, Fig. 1) kun lidet skiller sig i sit Udseende fra Hunnen, er For.skjellen raellem de to Kjøn i den slægtsmodne Tilstand saa skarpt udpræget (se Tab. I, Fig. 1 og 3), at man uden en noiere Undersøgelse knapt en- gang skulde tro, at de tilhørte samme Art. Kjons- forskjellen er udtrykt saavel i den hele Habitus som i Structuren af enkelte af Lemmerne, især de 2 Par Følere, der er modifieerede paa en meget lig- nende Maade som hos Hannerne af de fleste Amphi- poder. De største Hanner, jeg har fundet, havde en Længde af omtrent 12 mm.; men jeg har ved vor Sydkyst truffet Hanner af knapt mere end den halve Størrelse, skjondt fuldstændigt slægtsniodent ud- viklede. Legemets Form er (se Tab. I, Fig. 3) paafaldende sraækrere end hos Hunnen, og navnlig er Rygskjol- det kj endelig smalere, seet fra Siden af elliptisk Form, med Hoiden neppe halvt saa stor som Læng- den. Fremdeles er Bagkroppen noget længere i Forhold til Forkroppen, og dens forreste Afsnit kraftigere udviklet end hos Hunnen. Endelig giver de enormt forlængede Halegrene Dyret et fra Hun- nen meget afvigende Udseende. Øinene er fixldkommen af samme Bygning som hos Hunnen, men synes noget storre og har det ydre Parti stærkere udvidet. single oval joint whose inner edge is straight, whilst the outer edge is somewhat curved. To the last named 4 strong spines are secured, and 2 simi- lar ones issue from the point, of which the inner- most one is the longest. Between the spines there are also found here fine bristles directed outwards, whilst the bristles on the inner margin are greatly reduced. The caudal rami (fig. 12) are about same length as the two last posterior segments of the body taken together, and are usually strongly diver- gent. They are of narrow, linear form, quite slightly narrowed towards the extremity, and furnished roundabout with a series of short non-ciliated spines, which at the tip assume the form of greatly pro- longed bristles. Besides these there are found, along the inner edge, a series of considerably longer and finer, closely ciliated bristles. The coloiir of the animal is somewhat variable, from very pale yellowish to pretty intense red- brown. I have observed the most distinguished co- loured specimens in the Norwegian Arctic region. Description of tlie sexnall.v ripe male. Whilst the not yet sexually ripe male, al- though in other respects fully developed (see PI. II, fig. 1), distinguishes itself in appearance only slightly from the female, the difterence between the two sexes in the sexiiallj^ ripe condition is so sharply defined (see PI. I, fig. 1 and 3\ that without a close examination the observer would scarcely even believe that they pertained to the same species. The sexual difference is expressed both bj^ the en- tire habitus, as well as in the structure of some of the appendages, especially the two pairs of antennæ, which are modified in a very similar manner to that of the males of most Amphipods. The largest males I have found had a length of about 12 mm ; but. on our south coast I have met with males of scarcely more than half the size, although completely sexually developed The form of the body (see PL I, fig. 3) is con- spicuously more slender than in the female, and the carapace, especiallj', is perceptiblj^ narrower; viewed from the side the shape is elliptical, the height being scarcely half so great as the length. Further, the posterior division of the body is somewhat longer in relation to the anterior one, and its fore- most section more powerfully developed than in the female. Finally, the enormously prolonged caudal rami impart to the animal a very different appeai'- ance from the female. The eyes are of exactly the same structure as in the female, but appear to be somewhat larger, and have the outer portion more dilated. 22 De ovre Følere (Tab. IV, Fig. 1) er betydelig længere end hos Hunnen og, lige udstrakte, omtrent saa lange som Forkroppen og «Præabdomen» tilsam- men. Skaftet skiller sig ikke væsentligt i sin Byg- ning fra samme kos Hunnen, hvorimod begge de ter- minale Vedhæng er kjendelig forskjellige. Det blad- formige Vedhæng er forholdsvis betydelig større og mere forlænget, omtrent 4 Gange saa langt som bredt, eller paa det nærmeste af samme Længde som de to sidste Led af Skaftet tilsammen. For- øvrigt viser det den samme characteristiske tætte, kostformige Borstebesætning som hos Hunnen. Svø- ben er særdeles stærkt forlænget, mere end dobbelt saa lang som Skaftet og stærkt afsmalnende mod Enden. Den er sammensat af 17 vel begrændsede Led, hvoraf det Iste egentlig repræsenterer 3 med hinanden sammensmeltede Led. De 9 — 10 første Led er stærkt opsvulmede i sit ydre Parti og her l)esatte med en tæt Krands af yderst fine gjennem- sigtige Sandseborster. De ydre Led bliver efter- haanden overordentlig tynde og foi^længede; dog er sidste Led noget kortere end de umiddelbart fore- gaaende. De nedre Følere (se Tab. I, Fig. 3) er af hele Legemets Længde, Halegrenene iberegnede, og ud- mærker sig især ved den overordentlig tynde og forlængede, af talrige korte Led bestaaende Svøbe, der ialmindelighed er lige bagud rettet. Derimod skiller Skaftet sig (se Tab. IV, Fig. 2) kun lidet fra samme hos Hunnen. Dog er dets sidste Led noget tykkere og mangler de lange Fjærborster, der hos Hunnen udgaar fra Enden, i hvis Sted der blot fin- des nogle meget fine Haar. Kindbakkerne og Overlæben viser fuldkommen samme Udseende som hos Hunnen. Ogsaa de 2 Par Kjæver (Fig. 3 og 4) er hyg- gede paa samme Maade som hos Hunnen ; men begge Par er forholdsvis mindre og har navnlig Tygge- lappene meget svagere ndviklede samt kun forsynede med yderst smaa, simple Børster. Branchialfodderne (Fig. 5) har den egentlige Stamme, eller Endopoditen, betydelig svagere ud- viklet end hos Hunnen og neppe overragende Exo- poditen, Ogsaa er de paa den fæstede Bør.ster kor- tere og alle af ens Udseende, uden at de i Spidsen fæstede udmærker sig ved en paafaldende Længde. I Modsætning hertil er saavel Exopoditen som Epi- poditen sæi'deles store og deres Gjellestructur endnu mere udpræget end hos Hunnen. Bagkroppens Svømmefødder er idethele kraf- tigere udviklede end hos Hunnen (se Tab. I, Fig. 3), The superior antennæ (Pl. IV, fig. 1) are con- siderably longer than in the female, and when straightly extended are about as long as the anterior division of the body and the præabdomen taken together. Tlie pedxincle does not particul- arly distinguish itself in structure from that of the female while, on the other hand, both the terminal appendages are perceptibly diiferent. The lamelliform appendage is, relatively, considerably larger and more prolonged, about 4 times as long as it is broad, or nearly of the same length as the two last joints of the peduncle together. It exhibits otherwise the same characteristic, close, briTsh-like, bristly armatiire as in the female. The flagellum is particularly greatly prolonged, more than twice as long as the peduncle, and is greatly narrowed towards the extremity. It is composed of 17 well-defined joints, of which the first one really represents 3, which are coalescent with each other. The 9 — 10 first joints are greatly thickened in their outer portion, and are here covered with a close wreath of estremely fine, transparent sensory bristles. The outer joints become gradually extraordinarily slender and prolonged; but the last joint is some- what shorter than the immediately preceding ones. The inferior antennæ (see PI. I, fig. 3) are as long as the entire body, the caudal rami included, and are especially distingui-shed by the extraordi- narily slender and prolonged flagellum, consisting of numerous short joints, which is usually directed straight backwards. On the other hand the peduncle (see PI. IV, fig. 2) distinguishes itself only little from the same part in the female. Still its last joint is somewhat thicker, and is without the long plumose bristles which, in the female, issue from the extremity ; in place of them there are only found a few very fine hairs. The mandibles and upper lip exhibit exactly the same ap])earance as in the female. The 2 pairs of maxillæ. also (fig. 3 and 4) are constructed in the same manner as in the female; but both pairs are relatively smaller, and have, especially, the masticatory lobes much more faintly developed and only furnished with extremely small simple Ijristles. The branchial feet (fig. 5) have the stem-proper, or endopodite, considerably fainter developed than in the female, and scarcely reaching beyond the exo- podite. The bristles attached to it are also shorter and all alike in appearance, without those attached to the point distinguishing themselves by any re- markable length. In contrast Iie'rewitli the exopo- dite as well as the epipodite are jiarticularly large, and their gill-structure more distinguished than in the female. The swimming feet of the posterior division of the body are altogether more powerfully developed 23 men skiller sig forøvrigt ikke s^nulerligt i sin Bygning. De 2 Par rudimentære Bagkropslemmer (Fig. 6 og 7) er ligeledes noget storre end hos Hunnen, og sidste Par (Fig. 7) har her et tj-deligt afsat lidet Rodled, ligesom Iste Par. I sin Form og Bevæbning stemmer iøvrigt liegge Par temmelig noie overens med samme hos Hunnen. Halegrenene udmærker sig (se Tab. I, Fig. 3) ved en i Forhold til samme hos Hunnen meget paa- faldende Lærigde, idet de endog er saa lange som de 5 bagre Bagkropssegmenter tilsammen, eller næ- sten af Legemets halve Længde. I>e er (Tab. IV, Fig. 8), som hos Hunnen i hver Kant bevæbnede med en Rad af korte Torner, hvoraf dog de i Yder- kanten her er meget talrigere og finere end de i Inderkanten. Desuden tindes, som hos Hunnen, langs den indre Kant en Rad af temmelig lange og tynde Fjær horster. Farven er i levende Tilstand gjennemgaaende blegere end hus Hunnen og Legemet halvt gjennem- sigtigt. Indre Organer. Undersøgelsen af den indre Organisation er hos nærværende Dyreform forbunden med ganske sær- lige Vanskeligheder. Dyret er ialmindelighed ikke gjennemsigtigt nok til at at man kan umiddelbart stu- dere denne paa det levende Dyr. og ved Dissection af opbevarede Exemplarer kommer man ikke meget langt, paa Grrund af det complicerede System af Muskler, som omgiver og tildels fylder den i og for sig meget trange Kropshule. Hertil kommer endnu et meget stærkt udviklet, og med talrige Fedtkiigler fyldt Binde væv, som omspænder de forskjellige Or- ganer og kun vanskeligt lader sig skille fra samme. Heller ikke Snitniethoden har givet mig fuldt ud tilfredsstillende Resultater. Bedst har jeg kunnet faa undersogt den indre Bygning i sin Helhed ved af et stort Antal Exemplarer at udvælge enkelte ualmindelig gjennemsigtige og helst ganske unge Lidivider og undersoge disse directe under Mikro- .skopet i levende Tilstand. Ved at combinere disse Undersøgelser med hvad jeg har kunnet fremstille ved Dissection, har jeg endelig efter meget Besvær troet at faa nogenlunde Rede paa den indre Orga- nisation hos denne mærkelige Dyreform. Forst etterat disse Undersøgelser forlængst var afsluttede, erholdt jeg Prof. Claus's fortjenstfulde Arbeide: «Untei'suchungen zur Erforschung der genealogischen Grundlage des Crustaceen-Systeni», hvori den indre Organisation hos Nebalia i Korthed omtales, med Vedføielse af stærkt forstørrede Figurer af Han og Hun, fremstillede som transparente Objecter. De than in the female (see Pl. I, fig. 3), but do not other- wise distinguish themselves particularly in their structure. The 2 pairs of rudimentary, posterior append- ages of the body (figs. 6 and 7) are likewise some- what larger than in the female, and the last pair (fig. 7) have here a distinctly defined, small basal joint like the 1st pair. In their shape and armature both pairs correspond otherwise pretty exactly' with the same organs in the female. The caudal rami distinguish themselves (see PL I, fig. 3) by a very striking length in relation to the length of the same in the female, as the}- are even as long as the 5 backmost segments of the posterior body taken together, or nearly half the length of the body. They are (PI. IV, fig. 8), as in the female, armed on each edge with a series of short spines, of which, however, those on the outer edge are here much more numerous and finer than those of the inner edge. There are found, besides, as in tlie female, along the inner edge, a series of pretty long and thin. plumose setæ. The colour, in the live state, is, pervadingly, paler than in the female, and the body is semi- transparent. Internal organs. The investigations of the internal organization is in the present animal form attended with (juite special difficulties. The animal is generally insuffi- ciently transparent to enable us to study it directly in the living state; and on dissection of preserved specimens we make no great progress on account of the complicated muscular system which surrounds and partly fills the, in itself very narrow, body- cavity. To that is added still, a very stronglj^ developed, and with fatty globules filled, connective- tissue, which encloses the various organs, and per- mits itself with difficulty to be separated from them. Neither has the sectional method aftbrded me completely satisfactory results. I have been enabled to investigate the internal structure in its entirety best, by choosing from among a large number of specimens some more than usualh^ trans- parent, and preferably quite young, individuals, and bv investigating these in the live state directly under the microscope. By combining these investigations with what I have been able to ]n'esent by dissec- tion, I have finally after much difficulty, I believe, been able to obtain in some measure an elucidation of the internal organization of this remarkable ani- mal form. First after these investigations had long previously been concluded, did I obtain Prof. Claus's admirable work -Untersueliungen zur Erforschung der genealogischen Grundlage des Cnistaceen S3'- stem» in which the internal organization of Nebalia is shortly mentioned, and illustrated liy greatly mag- 24 Resultater, hvortil jeg er kommet, stemmer idethele temmelig vel overens med hvad Claus her har med- delt. Paa Tab. V fremstiller Fig. 1 en Hun seet fra Siden og stærkt foi-storret, med de forskjellige Organer indtegnede i samme og anlagte med for- skjellige Farver. Fig. 2 fremstiller et Tværsnit af Legemet omtrent over Midten af Truncus; de indre Organer er anlagte med samme Farve som paa Hovedfiguren. Tarmtractus- Spiserøret er meget kort og stiger fra Mund- aabningen lodret i Veiret, forbindende sig under en næsten ret "Vinkel med den forreste, i Hovedet lig- gende Del af Tarmen. Dette forreste Afsnit af Tarmtractus er for.synet med et temmelig compli- ceret Chitinskelet (Tab. V, Fig. 3, 4) og danner saa- ledes et Slags Tyggemave, noget lignende den hos Amphipoderne forekommende. Paa Chitinskelettet kan adskilles 3 Hoveddele, en forreste, en midterste og en bagerste Del. Den forreste Del er noget affladet og indeholder 2 fortil divergerende Lister, besatte med en dobbelt Rad af fine, tæt sammen- trængte Cliitinpigge. Lige ved Indgangen til Spise- røret tindes desuden ventralt 2 parvise Forlioininger, besatte med indadrettede Borster. Den midterste Del er temmelig stærkt opsvulmet og bagtil skraat afskaaret, dannende her en næsten klokkeformig Udvidning, hvorfra rager frem et Par tæt haarede Flige. Det er her at de til Tarmen horende Lever- sække forener sig for at udmunde i Tyggemavens Lumen. Den bagerste Del, endelig, danner en lang skedeformig, og i de frie Kanter med fine Børster besat tynd Flig, der kun indtager Dorsalsiden af Tarmen og med sin i en fin Spids udtrukne Ende rækker langt ind i selve Truncus. Tarmen danner forøvrigt et simpelt cjdindriskt, med stærke Ring- muskler forsynet Rør, der strækker sig igjennem hele Midtkroppen, Bagkroppen og Mesteparten af Halen. Ved Enden af næstsidste Halesegment for- binder den sig med en kort. stærkt muskuløs Ende- tarm, der aabner sig nedenunder Basis af Halegre- nene. Af Leversække findes ikke mindre end 4 Par, alle særdeles tynde og saa fast forbundne med Tar- men med fedtholdigt Bindevæv, at de yderst vanske- ligt lader sig isolere fra samme. Det forreste af disse Par er meget korte og rettede fortil over Tyggemaven, medens de 3 øvrige Par følger Tarmen bagud og ender omtrent ved Begyndelsen af Halen. Paa Tværsnit (Fig. 2) viser disse sidste (cd, cv) sig grupperede næsten i Form af en Rosette omkring og tæt ind mod Tarmen, med et noget større Mel- lemrum mellem det dorsale Par. nified figures of male aud female, presented as transparent objects. The results at which I have arrived agree, upon the whole, pretty well with what Clans has here stated. Plate V, fig. 1 repre- sents a female viewed laterally and greatly magni- fied, with the various organs drawn in the repre- sentation and coloured with diff'erent colours. Fig. 2 represents a transversal section of the body across nearly the middle of the truncus ; the internal organs are coloured with the same colours as in the chief figure. The intestinal tract. The oesophagus is very short and rises per- pendicularly from the oral aperture, connecting itself at almost a right angle with the foremost part of the intestine situated in the head. That foremost section of the intestinal tract is fur- nished with a pretty complicated chitinous skeleton (PI. 4, fig. 3. 4) and forms thus a kind of mastica- tory stomach, somewhat like what is present in the Amphipods. Three chief parts maj' be distinguished in the chitinous skeleton, a front one. a medial one, and a back one. The front portion is somewhat flattened and contains 2 fillets which diverge to the front and are beset with a double series of fine, closely crowded chitinous spikes. Exactl}^ at the mouth of the oesophagus there are further found, ventrally, 2 prominences in pairs, beset with bristles directed inwards. The medial part is pretty greatly swollen out and obliquely truncated behind, forming here a nearly bell-shaped dilation, from which a pair of densely hirsute flaps project. It is here that the liver-sacs pertaining to the intestine unite, in order to debouch into the cavity of the masticatory stomach. The posterior part finally forms a long sheath-like thin flap which is, on its free edges, beset with fine bristles, and only occupies the dorsal side of the intestine; and which, with its extremity drawn out to a fine point, extends far into the truncus itself. The intestine forms, other- wise, a plain cylindrical tube furnished with strong ring-muscles, which extends itself through the entire mesosome, the metasome, and the greater part of the urosome. At the extremity of the pen- ultimate caudal segment, it connects itself to a short, strongly muscular rectum which opens below the base of the caudal rami. Of liver-sacs there are no less than 4 pairs found, all of them particularly slender, and so firmly connected to the intestine b^^ fatty connective-tissue that it is extremely difficult to isolate them from it. The foremost pair of these sacs is very short and directed forwards above the masticatory stomach, while the 3 other pairs follow the intestine backwards and terminate at about the beginning of the urosome. In trans- versal sections (fig. 2) these last show themselves 25 Blodkarsystemet . Hjertet (Fig. 1, Fig. 2, c) er af langstrakt spiiidel- dannet Form og strækker sig, Timiddelbart ovenfor Tarmen, igjennem hele Midtkroppen og Størsteparten af Bagkroppen, endende omtrent ved Enden af den- nes 3die Segment. I Midtkroppens 5te Segment har det sin storste Vidde og viser her til hver Side en meget iøinefaldende Tværspalte. En lignende, men betydelig mindre Spaltaabning sees til hver Side helt fortil, ved Hjertets Begyndelse. Claus har desuden afbildet, mellem begge Par, 4 meget smaa dorsale Spaltaabninger, som det dog ikke er lykkets mig at faa se tydeligt. Fra Hjertets forreste Ende udgaar en, ialfald i sit inderste Parti tydelig Arterie, og ogsaa Hjertets bagre Ende har forekommet mig at fortsætte sig i en lignende bagudlobende Arterie. Noget virkeligt ndviklet Blodkarsystem synes dog neppe at være tilstede, og Blodet circnlerer, som hos andre lavere Crustaceer, væsentlig kun i væg- løse Hulrnm mellem Bindevævet og Musklerne. I Brancliialfodderne er allerede omtalt Tilstedevæ- relsen af saadanne med hinanden anastomoserende Blodgange, navnlig i de 2 ydre Vedhæng (Exopodit og Epipodit). Et lignende System af væglose Blod- kanaler tindes ogsaa mellem Rygskjoldets 2 Lamel- ler, og da Cirkulationen her er meget livlig, har man Grund til at antage, at Rygskjoldet spiller en ikke uvæsentlig Rolle ved Dj'rets Respiration. Nervesystemet. At undersoge Nervesystemet i sine Detailler, er forbundet med særdeles store Vanskeligheder, da dets Centraldele ligger saa tæt omgivne af Muskler og Bindevæv, at de yderst vanskeligt lader sig isolere ved Disection. Paa Tværsnit af Kroppen (Pl. V, Fig. 2) kan man dog let orientere sig angaaende Buggangliekjædens Beliggenhed (g), og kan herefter bestemme dens Plads ogsaa i Profil af Dyret (se Fig. 1). Hjernegangliet har det kun lykkets mig at se temmelig ufuldstændigt. Det synes ikke at være af nogen betydelig Størrelse, og udsender, for- uden Synsnerverne, stærke Nervestammer til de 2 Par Følere. I Midtkroppen ligger de enkelte Knuder af Buggangliekjæden tæt sammen, kun for- bundne med meget korte og tykke Længdecommis- surer, mellem hvilke der knapt er noget Mellemrum. Selve Ganglierne er forholdsvis smaa og alle af ens Størrelse, deres 2 Halvdele fuldkommen sammen- 4 — G. 0. S.ars: Fauna Xorveriia\ (cd, cv), grouped nearly in the form of a rosette, around and close in to the intestine, with a somewhat largish interval between the dorsal pair. The blood-vessel system. The heart (fig. 1, fig. 2 c) is of elongate, fusi- form shape, and extends, immediately above the intestine, through the entire mesosome and the greater part of the metasome, terminating at aboat the extremity of the 3rd segment of the latter. It has its greatest breadth in the 5th segment of the mesosome, and exhibits here on either side a very prominent transversal fissure. A similar, but considerably smaller fissure-aperture is seen on each side, quite in front, at the commencement of the heart. Claus has illustrated besides, between both pairs, 4 very small dorsal fissure-apertures, which I have, however, not been fortunate enough to ob- serve distinctly. From the foremost extremity of the heart there issues a, at least in its innermost portion, distinct artery; and also the posterior ex- tremity of the heart has appeared, to me, to con- tinue itself in a similar backward running artery. Any real, developed blood-vessel system scarcely appears, however, to be present; and the blood circulates, as in other lower Crustaceans, princi- pally, only in cavities, without walls, between the connective-tissue and the muscles. In the branchial feet, the presence of such blood pasages, anastom- osing with each other, has already been mentioned; especially in the 3 outer appendages (exopodite and epipodite). A similar sj'stem of blood-ducts, without walls, is also found between the 2 lamellæ of the carapace, and as the circulation is here very active there is reason to suppose that the carapace plays a not unimportant part in the respiration of the animal. The nervous system. To investigate the nervous .system in its details is a matter of particularly great difficulty, as its central portions lie so closely surrounded by muscles and connective tissue that it is excessively difficult to isolate them by dissection. In transversal sec- tions of the body (PI. V, fig. 2) we can, however, easily obtain information concerning the situation of the ventral ganglial chain (g), and can from this deter- mine its situation also in a side-view of the animal (see fig. 1). I have not been fortunate enough to observe the ganglion of the brain ver}^ pei'fectly. It does not appear to be of any considerable size, and sends off, besides the optical nerves, powerful ner- vous stems to the 2 pairs of antennæ. In the meso- some, the individual knots of the ventral ganglial chain lie close together, only connected by very short and thick longitudinal commissures, between which there is scarcelj^ any interval. The ganglia 26 smeltede med binandeii og udsendende 2 stærke j Sidestammer, der udbreder sig dels i Brancliial- fadderne, dels i Kroppens Muskulatur, De 4 i Bag- kroppen beliggende G-anglier er betydelig større og ogsaa mere fjernede fra liinanden, med længere og mere tydeligt skilte Commissurer. I Halen løber 2 Nervestammer langs ad Bugsiden lige til Hale- grenene, og danner for hvert Par af de smaa Hale- fødder en liden ganglios Opsvulmning. En lignende sj'nes ogsaa at lindes ved Basis af Halegrenene. Generationsorganerne. Ovarierne er til sine Tider meget let at obser- vere kos det levende Dyr, da de med stor Tydelig- bed skinner igjennem Integumenterne paa Grund af sin intense rødgule Farve. De danner (se Pl. V, Fig. 1, Fig. 2, ov) 2 langstrakte Sække, der stræk- ker sig, til hver Side af Tarmen, igjennem hele Midtkroppen og Bagkroppen og rager endog et Stykke ind i Halen. I enhver af Sækkene findes kun en enkelt Række, sig udviklende Æg, alle med tydelig Kiniblære og grovkornet Blommemasse. Ægge- lederne har det ikke lykkets mig at faa se saa tyde- . ligt, at jeg med Bestemthed kan angive deres Plads. Det har imidlertid forekommet mig. at de udmunder ved Basis af Gte Par Branchialfodder. Testes har omtrent samm^ Beliggenbed som Ovarierne og dan- ner ligesom disse simple Sække, men er betydelig smalere end disse. De munder, ifolge Claus ved Basis af sidste Par Branchialfodder. Ud vikling. Æggene optages, som ovenfor nævnt, efter at være komne ud af Æglederne, i et Slags Rugehule, der ligger ind under Midtkroppen, omgiven af Ryg- skjoldets Valvler og delvis begrændset af Branchial- fodderne, hvis talrige krummede Endebørster liindrer dem fra at falde ud af Rygskjoldets Hule. De undergaar her sin hele Udvikling, og førsst naar Un- gerne er saa vidt komne, at de med Lethed kan be- væge sig i Våndet, forlader de Klækkehulen. Ud- viklingen er noiere studeret af den russiske Natur- for.sker Kowalewsky, og mine Undersogelser stemmer i alt væsentligt overens med hvad der af denne ud- mærkede For.sker er meddelt. Æggene er Timiddel- bart efter at være optagne i Klækkehulen, af rødgul Farve og noget oval Form. Senere antager de lidt efter lidt en noget lysere Couleur og bliver ogsaa mere gjennemsigtige. De er, som hos Flerheden af Crustaceerne, meroblastiske, idet Størsteparten af themselves are relatively small and all alike in size; their 2 halves are completely coalescent Avith each other, and send off 2 powerful lateral stems which distribute themselves partly in the branchial feet and partly in the muscles of the body. The 4 ganglia situated in the metasome are considerably larger and also situated farther apart from each other, with longer and more distinctly separated commissures. In the urosome 2 nerve-stems pass along on the ventral side, right to the caudal rami, and form, for each pair of the small caudal feet, a small gangliar swelling. A similar swelling ap- pears also to be present at the base of the caudal rami. The reproductive organs. The ovaries are at times very easy to observe in the living animal, as they shine through the inte- guments with great distinctness, owing to their intense red-yellow colour. They form (see PI. V, fig. 1, fig. 2, ov) 2 elongate sacs which extend them- selves to each .side of the intestine through the entire mesosome and metasome, and reach even some way into the urosome. In each of the sacs there is found only a single series of developing ova, all having a distinct germinative vesicle and coarsely granular yolk substance. The ovarial ducts I have not been fortunate enough to observe so distinctly that I can with precision state their situation. It has, however, appeared to me that they debouch at the base of the 6th pair of branchial feet. The testicles have nearly the same situation as the ovaries and, like these, form plain sacs, but are considerably narrower than them. According to Claus they debouch at the base of the last pair of branchial feet. Development. The ova are received, as above stated, after having been discharged from the ovarial ducts, in a kind of hatching cavity, which is situated in below the mesosome. surrounded by the valves of the carapace and partly limited by the branchial feet whose numerous bent terminal bristles prevent them from falling out of the cavity of the carapace. They undergo here their entire development, and first when the young ones have advanced so far that they can move themselves with ease in the water do they abandon the hatching cavity. The development has been closely studied by the Russian naturalist Kowalewsky, and my investigations agree in all material points with what has been stated by that eminent investigator. The ova are, imme- diately after liaving been received into the hatching cavity, red-yellow in colour, and somewhat oval in shape. Subsequently they, little by little, assume 27 Æggets Blommemasse ikke undergaar nogen Klov- ning. Ifolge Kowalewsky dannes det blastodermale Cellelag ved den successive Kløvning af en enkelt stor Polarcelle. Paa et temmelig tidligt Udviklings- stadium, som er ft-emstillet Pl. V, Fig. G, tinder vi, at Blommemassen i den ene Halvdel af Ægget er bægerformigt omgivet af et Lag af klare Celler, der navnlig i Kanten af Ægget tydeligt hæver sig af fra den mere rrgjennemsigtige rodgule Blommemasse. Dette er den sig dannende Blastoderm. Det første Anlæg til Embrj'onet antydes ved en svag trans- versal Indbugtning i Blastodermen, begrændset af 2 noget fremspringende Vulster. Den ene af disse Vulster forestiller Overlæben, den anden Haleenden (se Fig. 7 og 8). Til hver Side af den ovenomtalte Indbugtning viser sig noget senere 3 tværstillede langagtige Forhøininger. der forestiller Anlægget til de 2 Par Folere og Mandibularpalperne, og foran dem sees til hver Side en utydeligt begrændset rundagtigUdvidning, der aabenbart er Anlægget til Øienstilkene. Embrj'onet, der endnu er omgivet af Æggehinden, betinder sig nu i det saakaldte Nauplius- stadium. Senere optræder, bag de 3 Par ovenomtalte Lemmeanlæg, successivt en dobbelt Række af min- dre Forhøininger, der antyder Anlægget til de føl- gende Lemmer (se Fig. 7). Samtidigt bliver den transversale Lidbugtning dybere, Haleenden sondrer .sig tydeligere og stræber at fjerne sig fra Over- læben, hvad der tilsidst, i Forbindelse med Embry- onets Væxt, har tilfolge at Æggehinden bri.ster og skaller af. I)et Stadium, som nu følger, er det saa- kaldte Puppestadium, som er fremstillet Fig. 'J og 10. Embryonet, som nu kim er omgivet af en over- ordentlig tynd og gjennemsigtig Membran, Larve- huden, viser ikke længere den oprindelige ventrale Krumning, men har strakt sig fuldt ud i Længden og endog antaget en svag dorsal Bi lining. Formen er næsten kolledannet, idet Legemet fertil ligesom er opblæst, paa Grund af en betydelig Rest af Blommemassen, der fylder det her dorsalt. Man kan saaledes egentlig paa Legemet adskille to tem- melig skarpt sondrede Hoveddele, en næsten kugle- formigt opsvulmet forreste Del, og en betydelig smalere, næsten cylindrisk og bagtil i en stump Spids udgaaende Del. Den første svarer nærmest til Hovedet hos det voxne Dyr, medens den sidste i sig indbefatter baade Midtkrop, Bagkrop og Hale. Saavel paa den forreste som bagerste Del kan der nu adskilles en dobbelt Række af lemmelignende Fremspring, men af et endnu yderst ufuldkomment Udseende, kim dannende simple koniskt tilløbende Fortsatser. Størst og tydeligst sondrede er de 2 forreste Par (a\ a^) som forestiller de 2 Par Folere. De har en næsten pølsedannet Form og er bolede bagud langs Siderne af Forkroppen. Imellem dem i Midten sees et tj^deligt klapformigt Fremspring (L), som er Overlæben, og foran dem til hver Side en a somewhat lighter colour and also become more transparent. They are, as in most of the Crustacea, meroblastic, as the greater part of the ovum's yolk does not undergo any segmentation. According to Kowalewsky, the blastodermatic cellixlar layer is formed by the successive segmentation of a single large polar cell. In a pretty early stage of devel- opment, which is represented in PI. 4, fig. 6, we find that the j'olk in the one half of the ovum is sur- rounded by a cup-shaped layer of clear cells which, especiallj' on the edge of the ovum, distingiiish themselves from the more opaque red-yellow yolk. That is the Blastoderm in course of formation. The first rudiments of the embryo is indicated by a faint transversal inciirvation of the blastoderm, limited by 2 projecting swellings. The one of these swellings represents the upper lip, the other the cairdal extremity (see fig. 7 and 8). On each side of tlie above-mentioned in-curvature there, somewhat later, appear 3 transversally placed, elongate pro- minences which represent the rudiments of the 2 pairs of antennæ and the palpi of the mandibles; and in front of them there is seen on either side an indi.stinctly limited, roundish dilatation, which is evi- dently the rudiment of the ocular peduncles. The embryo, which is still surrounded by the skin of the oviim, finds itself now in the so-called Nauplius stage. Subsequently there appears, behind the rudi- ments of the 3 pairs of appendages above mentioned, successively, a double series of smaller prominences, which indicate the rudiments of the succeeding appen- dages (see fig. 7). At the same time the transversal in-eurvatnre becomes deeper, the caudal extremity separates itself more distinctly and endeavours to remove itself from the upper lip, with the eventual ettect, in connection with the growth of the embryon, that the skin of the ovum bursts and scales ofl'. The stage which now succeeds is the so-called piipa stage, represented in fig. 9 and 10. The embryo, which is now only surrounded by an extraordinarily thin and transparent membrane, the larval skin, no longer exhibits the original ventral ciirvature, but has stretched itself fully out in length, and even as- sumed a faint dorsal curvature. The shape is almost clavate, as the body in front is, as it were, blown out, owing to a considerable remnant of the yolk substance which here occupies it dorsally. We can thus in the body really distinguish two pretty sharply separated chief parts, an almost globularly shaped swollen front part, and a considerably narr- ower, almost cylindrical, part passing out in a blunt point behind. The first named corresponds closest to the head of the adult animal, while the last- named contains within itself the mesosome, the metasome and the urosome. In the front, as well as in the posterior part, there can now be dis- tinguished a double series of limlvlike prominences 28 temmelig stor rnndagtig Forlioining (0), Anlægget til Øienstilkeiie. Bag Folerne følger 3 Par ligeledes pølsedannede, men betydelig mindre Vedhæng, hvori man let erkj ender Anlægget til Mandibularpalperne (Mp) og de 2 Par Kjæver (m', m^). Langs Siderne af den bagre Del af Legemet sees en nafbrudt Række af ialt 11 Par simpelt koniske Fortsatser, hvoraf de S forreste er af fuldkommen ens Udseende os staar næsten ret ud til Siderne, medens de 3 ba- gerste Par er mindre tydeligt fremragende og mere nedadrettede. Alle disse Fortsatser er egentlig kun simple poseformige Udkrængninger af Larvehuden, og først ijulenfor dem sees Anlægget til et til- svarende Antal Lemmer. De forstnævnte 8 Par Fortsatser (brp) sjmes at svare til et lignende Antal Branchialfodder, medens de 3 bagerste Par (pl) aabenbart antyder ligesaamange Svommefodder. Den bagenfor liggende Del af Puppens Legeme er uden ethvert Spor af Fortsatser og simpelt koniskt tilløbende. Indenfor den gjennemsigtige Larvehud, som temmelig løst omgiver den bagre Del af Em- bryonets Krop, er allerede en tydelig Segmentering bemærkelig, og man kan herved temmelig noie be- stemme Grændsen mellem de forskjellige Kropsafsnit. Kun det bagerste Afsnit, Halen er endnu ufuldkom- ment segraenteret. I den forreste Del af Legemet sees til hver Side, ligeledes indenfor Larvehuden, en utydelig halvcirkelformigt buet Linie (c), der fore- stiller den frie Kant af det sig udviklende Ryg- skjold, og helt fortil, umiddelbart ovenover Anlægget til Øienstilkene, er der et lidet knudeformigt Frem- spring (R), der aabenbart forestiller den sig udvik- lende Pandeplade. I Axen af den bagre Del af Le- gemet har allerede Tarmen anlagt sig i Form af en med et klart lysegult Lihold fyldt simpel Kanal, der dog endnu er lukket i sin bagre Ende, medens den fortil staar i aaben Kommunication med den rummelige, af Blommemasse fyldte' Hule, der ind- tager den dorsale Del af Hovedet. Fig. 11 forestiller det umiddelbart efter Puppestadiet følgende Udvik- lingstrin. Hvad der væsentlig adskiller dette Sta- diiim fra det foregaaende, er, at Larvehuden nu er afkastet, saa at de forskjellige Kropsvedhæng alle er frit fremragende, ligesom Legemets Segmentering ogsaa udvendigt er tydelig. Den dorsale Krumning af Embryonet er nu saa stærk, at Legemet næsten beskriver en fuldstændig Halvcirkel. De til Hove- det hørende Lemmer har voxet adskilligt i Størrelse, men er forøvrigt kun lidet forandrede. Dog bemær- kes paa det forreste Par (a') en liden Bigren, som antyder det bladformige Appendix. Branchialfødderne (brp) er tilstede i sit fulde Antal (8 Par) og viser sig alle dybt tveklaftede, samt lige nedadrettede. Derimod findes der endnu kun anlagte 3 Par Svomme- fodder (pl), idet det 4de Par først meget senere ud- vikler sig. Heller ikke sees noget Spor af Hale- fødder. Halen selv har imidlertid nu sit fulde Antal which however have, as yet, an extremely im- perfect appearance, forming only plain conically shaped prolongations, The 2 foremost pairs (a', a'-) which represent the 2 pairs of antehnæ, are the largest and most distinctly separated. They have almost a sausage-shape, and are curved backwards along the sides of the anterior body. Between them, in the middle, there is seen a distinct flap-shaped pro- minence (L.), which is the upper lip, and in front of them, on either side, a pretty large roundish pro- minence (0), the rudiments of the ocular stems. Be- hind the antennæ succeed 3 pairs, likewise sausage- shaped, but considerably smaller appendages, in which we easily recognize the rudiments of the man- dibular palps (Mp) and the 2 pairs of maxillæ (m', m^). Along the sides of the posterior part of the body there is seen a continuous series of 11 plain, conical projections in all, the H foremost ones of which are of exactly the same appearance and stand almost straight out at the sides, while the 3 backmost pairs are less distinctly projectant and directed more downwards. All these projections are really only ])lain bag-shaped bulgings of tlie larval-skin, and tirst to the inside of them is there seen the rudi- ments of a corresponding number of appendages. The first named 8 pairs of projections (brp) corre- spond, it would seem, to a similar number of branchial feet, whilst the 3 backmost pairs (pi) evi- dently indicate tlie same number of swimming feet. The portion of the body of the pupa situated behind is without the least trace of projections and runs oiit in plain conical form. Liside of the transparent larval skin, which pretty loosely surrounds the pos- terior portion of the bodj^ of the embryot, there is already a distinct segmentation noticeable, and we can by it pretty distinctly determine the demarcation between the various divisions of the bodj^ The backmost division only, the urosome, is as yet imper- fectly segmented. In the anterior part of the body there is seen on either side, likewise inside the larval skin, an indistinct, semicircular curved line (c), which represents the free edge of the carapace in course of development; and quite in front, immediately above the rudiments of the ocular stems, there is a small nodular prominence (R) which evidently re- presents the frontal plate in course of development. In the axis of the posterior jiart of the body the intestine has alreadj^ begun to appear in the form of a plain canal, filled with a clear light yellow substance, whicli is still closed at its posterior ex- tremity, whilst, in front, it stands in open commu- nication with the roomy cavity filled with yolk substance wliich occupies the dorsal part of the head. Fig. ] 1 represents the stage of development imme- diately succeeding the ])U])a stage. What chiefly dis- tinguishes this stage from the preceding one is, that the larval skin is now thrown off, so that the various 29 Segmenter, og Halegrenene er tydeligt afsatte samt liver i Spidsen forsj'iiet med en kort Borste. Pande- pladen (R) er nu tj^deligt fremragende, og Øienstil- kene (0) har antaget en noget konisk Form samt viser i sin ydre Del den første svage Antydning til Dannelse af Synselementer. Til hver Side af Tar- men bemærkes i Midtkroppen en temmelig plump og kort cylindrisk Sæk, der aabenbart forestiller en af Leversækkene. Den dorsale Del af Forkroppen er endnu stærkt opblæst og fyldt af rcdgul Blomme- masse. Umiddelbart nedenfor denne Del sees nu tydeligt de frie Kanter af Rygskjoldet. De Foran- dringer, Embryonet endnii har at gjennemgaa, er ganske successive. Den tilbageværende Rest af Blommemassen opbrviges lidt efter lidt, og samtidigt aftager den dorsale Opsvulning af Hovedet i Stør- relse, medens Rygskjoldets Val vier mere og mere voxer Ild over Siderne af Midtkroppen. De forskjel- '■ lige Ivropsvedhæng udformes og indtager den for dem characteristiske Stilling i Forhold til Legemet, hvorved ogsaa meget snart Nebalia-Habitusen bliver fremtrædende. Fig. 12 fremstiller Ungen, naar den er færdig til at forlade Klækkehulen. Man har ingensomhelst Vanskelighed med i den at erkjende en ung Nebalia. Den eneste væsentlige Afvigelse er, at der fremdeles kun er 3 Par Svømmefodder tilstede. Af det 4de Par sees kun et ubetydeligt Anlæg bag de øvrige, i Form af et Par smaa knude- formige Fremspring (pM. Ungen kan nu bevæge sig frit i Våndet og ernære sig selv; men det varer endnu adskillig Tid, inden de forskjellige Vedhæng opnaar sin fulde Udvikling og faar sin normale rige- lige Borstebesætning. Af alle Vedhæng er 4de Par Svommefødder de, som udvikler sig senest. appendages of the body are all freely projectant, while, also, the segmentation of the body is distinct externalh'. The dorsal curvature of the embryo is now so great, that the body almost describes a com- plete semi-circle. The appendages pertaining to the head have considerably increased in size, Init are otherwise only little changed. Still there may be noted on the foremost pair (a') a little sub-branch that indicates the lamelliform appendage. The branchial feet (brp) are present in their full number (8 pairs) and show themselves to be all deeply fissured and directed straight downwards. On the other hand, there are as yet only found 3 pairs of swim- ming feet (pi) in a rudimentary state, as the 4tli pair only much later becomes developed. Neither is there any trace of caudal feet observed. The urosome itself has now, however, its full number of segments, and the caudal rami are distinctly projected and each furnished with a short bristle at the tip. Tiie frontal plate (R) is now distinctly projectant, and the ocular stems have now assumed a somewhat conical form and in their external part exihibit the first faint indication of the formation of visual elements. In the mesosome, on each side of the intestine, there is noticed a pretty stout and short cylindrical sac, which evidently represents one (if the liver sacs. The dorsal part of the an- terior body is still greatly blown out and filled with red-yellow yolk substance. Immediately below that part the free edges of the carapace are now dis- tinctly seen. The changes that the embryon has yet to undergo are quite successive. The remains of the yolk substance are little by little used u]), and the dorsal swelling of the head becomes at same time reduced in size, while the valves of the carapace grow more and more out over the sides of the mesosome. The various appendages of the body become fully formed and occupy the characterstic position in relation to the body pe- culiar to them, causing thus the Nebalia habitus A^ry soon to become prominent. Fig. 12 represents the 3'oung one when it is ready to abandon the hatching cavity. We have no difficulty whatever, in recognizing in it a young Nebalia. The only material divergence is, that there are still only 3 pairs of swimming feet present. Of the 4th pair there is only seen a faint rudiment behind the others, in the shape of a pair of small nodular prominences (p'). The young one can now move itself freely in the water, and nourish itself; but some time still jjasses, before the various appendages attain their full develophient and acquire their nor- mal, abundant bristle-covering. Of all the append- ages, the 4th pair of swimming feet are those which develope themselves latest. 30 Forekomst os; LeTCvis. Den her omhandlede mærkelige Dyreform fore- kommer ikke sjelden langs vor hele Kyst, fra Chri- stianiafjorden til Vadsø, men synes idethele at op- træde baade hyppigst og kraftigst udviklet i vor arktiske Region. I stor Mængde har jeg saaledes fundet den paa en Plads i Lofoten, Brettesnæs, hvor mange hundrede Individer indsamledes i Løbet af et Par Dage, og ogsaa ved Finmarken har jeg paa sine Steder trnffet den i mængdevis. Den pleier at holde til paa maadeligt Dyb, fra 10 til 30 Favne, og helst paa saadanne Steder, hvor Bunden er dækket af forraadnende Tangarter, hvoraf den for en væsent- lig Del synes at ernære sig. Ligesom Tilfældet er med flere andre Crustaceer, synes Hannerne kun til visse bestemte Tider af Aaret at opnaa fuld Slægts- modenhed, og optræder da kun ganske enkeltvis. Der- imod er endnu ikke slægtsmodent udviklede Hanner at finde til enhver Tid af Aaret og næsten i samme Antal som Hunnerne. I Maaden at bevæge sig paa, ligesom i sin hele ydre Habitus, har dette Dyr en umiskjendelig Lighed med en colossal Copepode; navnlig er den habituelle Overensstemmelse med visse Harpacticider meget paafaldende. Ligesom hos disse .sidste, er Legemet overordentlig bøieligt, navn- lig i dorsal Retning, og kan ofte krummes saa stærkt, at Halegreneue kommer i Contact med Pandepladen. Bevægelsen sker stødvis ved kraftige og temmelig rythmiske Slag af Svommefødderne, hvorved Lege- met drives frem med temmelig betydelig Fart. De slægtsmodne Hanner er overotdentlig raske i sine Bevægelser og foretager ofte længere Udflugter i Våndet. Derimod holder Hunnerne og de endnii ikke fuldt udviklede Hanner sig i Regelen ved Bunden og bevæger sig her mellem Bundmaterialet, ialmin- delighed paa Siden. De forstaar herunder med stor Behændighed at skjule sig mellem Mudret eller de hensmuldrende Tangrester, som bedækker samme, saa det slet ikke er saa let at finde dem freni, trods den ikke ubetydelige Støn-else. Lettest opdager man dem ved at slaa det optagne Bundmateriale ud i et fladt Kar, med en nbetydelig Kvantitet af Sjø- vand. De tilstedeværende Exemplarer vil da, især naar man rører lidt om i Bundsatsen, snart vise sig paa Overfladen af Våndet, og da de i Lighed med forskjellige andre Crustaceer ikke formaar at komme ned i Våndet igjen, efterat de først er komne i Be- rorelse med Luften, kan de med Lethed opsarales i levende Tilstand. Bringer man et helst yngre In- divid i en passende Kvantitet Sjøvand under Mikro- skopet, kan man saa noiere studere de forskjellige Livsytringer og kan gjennem de halvt gjennemsigtige Integumenter observere Hjertets Pulsationer, Tar- mens perestaltiske Bevægelser og Branchialfoddernes Spil. Di.sse sid.ste, der ingensomhelst Inllydelse bar paa Locomotionen, vil man i Regelen finde i en Distrilmtiou and Labits. The remarkable animal form spoken of here appears not rarely along our entire coast, from the Christianiafiord to Vadso, but seems, on the whole, to appear most frequently, and most powerfully de- veloped in our Arctic region. I have thus fonnd it in great abundance at a place, Brettesnæs in Lo- foten, where many hundreds of individuals were col- lected in the course of a couple of days; and also in Finmark I have, in certain places, met with it in great abundance. It is accustomed to keep itself at a moderate depth, from 10 to 30 fathoms, and preferably in those places where the bottom is co- vered with decomposing sea-weed of which it appears, to a material extent, to nourish itself. Like what is the case with several other Crustaceans, the males appear to only attain full power of reproduction at certain fixed seasons of the year, and are then met with only quite solitary. On the other hand, not fully reproductively ripe developed males are to be found at all seasons of the year, and almost in equal number to the females. In manner of movement, as well as in entire extei'nal habitus this animal has an unmistakable likeness to a colossal Copepod, especially is the habitual agree- ment with certain Harpacticidæ very striking. Like as in those last, the body is extraordinarily fiexible, especially in dorsal direction, and may ofen be so strongly bent that the caudal branches come into contact with tiie frontal plate. The movement takes place in jerks, with powerful and tolerably ryth- mical strokes of the swimming feet, by which the body is drawn forwards with pretty considerable speed. The reproductively ripe males are extra- ordinarily active in their movements, and frequently make long excursions in the water. On the other hand, the females and the not yet fully developed males remain, as a rule, at the bottom, and move here among the material of the bottom, generally on the side. In doing this they understand to con- ceal themselve.s with great dexterity in the mud, or the decomposing remains of sea-weed which covers it, so that it is not at all easy to search them out, in spite of the not inconsiderable size. We find them easiest by pouring the collected bottom mate- rial into a flat vessel, along with an inconsiderable quantity of sea-water. The specimens present will then, especially if the bottom stufi" is stirred a little up, soon show themselves on the surface of the water, and as they, like several other Crustaceans, are unable to swim downwards in the water again after they have first come into contact with the air, they may with ease be collected in the live state. If we place, ]n'eferably a young individual, in a suitable ijuantity of sea-water, under the microscope, we can then more closely study the various features 31 regelmæssig svingende rythnnsk Bevægelse, som kun j for kortere Tid ganske kan stoppes. Denne Be- vægelse har væsentlig respiratoriske Formaal, men er ogsaa af stor Betydning for Næringsoptagelsen. Ved disse Lemmers Spil frembringes nemlig inden- for Rygskjoldets Val vier en fertil gaaende Strøm- ning af Våndet, hvormed de Smaapartikler, der tje- ner Dyret til Fode, hvirvles indenfor Munddelenes Oraraade. Våndet strømmer herunder i en conti- nuerlig Strom ud fra Rygskjoldets forreste Ende, nedenfor Pandepladen. Derfor holdes denne altid, Tinder BranchialfoddernesBevægelse, lige fortil strakt, medens den i Regelen, saasnart Bevægelsen stopper, boies nedad, hvorved den som en Klap tillukker den forreste Aabning af Rygskjoldet. Udbredning. Arten synes at have en ganske overordentlig vid geograjihisk Udbreduing. Foruden ved Norges Kyster er den observeret i de arktiske Have, ved Gronland, Spitsbergen og Island, frem- deles ved Nordamerikas Østkyst, ved de britiske (Jer, og idethele langs hele Europas Nordsø- og Atlanterhavskyst, ligesom den ogsaa forekommer i Middelhavet, hvor den paa sine Steder, som i Golfen ved Neapel, ikke er ualmindelig. 2. Xebalia typhlops, G. 0. Sårs. (PI. 1, Fig. 4, Pl. IV, Fig. '.)— li)). Nehalla tyxihlops, G. 0. Sårs, Nye Pybvandscrustaceor fra Lo- foten; Chr. Vid. Selsii. Forh. f. 1869. Artscharacteristik, Meget lig foregaaende Art i sin almindelige Habitiis, skjondt maaske lidt mere vindersætsig af Form. Rygskjoldet, seet fra Siden, af oval Form, lidt lavere fortil og med de nedre Kanter jevnt buede paa Midten. Pandepladen vel udviklet, aflang oval, stærkt hvælvet oventil og for- synet i Enden med et spidst tornformigt Fremspring, Øinene yderst smaa og rudimentære, koniskt til- lobeude i Enden, og uden Spor af Pigment eller Synselementer. De øvre Følere (høs Hunnen) for- holdsvis kortere end hos foregaaende Art, med Svo- ben neppe længere end Skaftet og kun sammensat af 10 Led, det bladformige Appendix temmelig for- længet, næsten halvt saa langt som Svøben. De nedre Folere omtrent som hos N. hipes. Branchial- fodderne med Endopoditen meget tyiid og stærkt forlænget, ombøiet i Spidsen og forsynet med lange divergerende Fjærbørster; Epipoditen med den dor- of life, and may through the semi-transparent inte- guments observe the pulsations of the heart, the peristaltic movements of the intestine, and the play of the branchial feet. These last, which have no influence whatsoever on the locomotion, we will usually find in a regvilar, swinging, rythmical mo- tion, which only for a short time may be quite stopped. That motion has chiefly a respiratory func- tion, but is also of great impoitance in securing the nourishment. By the plaj^ of these appendages there is produced, namely, inside of the valves of the carapace, a forward current of the water by which the small particles that serve the animal for food are drawn within the area of the oral parts. The water during this flows out in a continuous stream from the foremost extremity of the carapace below the frontal plate. It is therefore always held stretched straight forward during the motion of the branchial feet, whilst, as a rule, as soon as the motion ceases, it is bent downwards, by which action it, like a cover, closes the foremost aperture of the carapace. Distribution. The species seems to have quite an extraordinarily extensive geographical distribu- tion. Besides on the Norwegian coasts, it is ob- served in the Arctic seas, at Greenland, Spitzbergen and Iceland; further, off the east coast of North America, at the British Islands, and, as a whole, along the entire North sea and Atlantic coasts of Europe; and, it likewise occurs in the Mediter- ranean, where it, in certain places, such as the (-i-ulf of Naples, is not uncommon. 2. Nebalia typlilops, G. 0. Sars. (PI. I, 13g. 4, PL IV, figs 9—19). Nehalia typhlops, G. O. .Sars, Nye Dyb\andscrustaceear fra Lo- foten; Chr. Vid. Selsli. Forh. f. 1809. Specific Characters. Very like the preceding species in its general habitus, although, perhaps, a little more stumpy in sliape. Carapace, viewed latei'ally, oval in form, a little lower in front, and with the lower edges evenly curved at the middle. Frontal plate well developed, oblongo-oval, strongly arched above, and furnished at the extre- mity with a pointed spiniform prominence. Eyes extremely small and rudimentary, passing into co- nical form at the end, and without trace of pig- ment or visual elements. Superior antennæ (in female) relatively shorter than in the preceding species, with the flagellum scarcely longer than the peduncle and only com])osed of 10 joints; the la- melliform appendage rather prolonged, almost half the length of the flagellum. Inferior antennæ about as in N. hipes. Branchial feet with the endopodite very slender and greatly prolonged. B2 sale Lob betydelig større end den ventrale. Første Par Svømmefodder med Yderkanten af den ydre Gren kun forsynet med 3 Smaatænder, umiddelbart ovenfor den Iste Endetorn. Halegrenene noget kor- tere end de 2 bagerste Segmenter tilsammen, Far- ven hvidagtig, iiden Pigmentering. Dyrets Længde 9 mm. Bemærkninger. Den her omhandlede Art staar vistnok meget nær foregaaende, men er dog let kj endelig fra samme ved forskjellige vel iidprægede Characterer, hvoraf navnlig maa fremhæves den rudimentære Beskaffenhed af Øinene og Pandepladens Form og Bevæbning. Ogsaa i Bygningen af de for- skjellige Kropsvedhæng vil man ved en noiere Sam- menligning kunne paavise en Del mindre Difterentser fra samme hos N. hipes. Beskrivelse. Legemets Form hos Hunnen (se Pl. 1, Fig. 4) stemmer idethele temmelig nøie over- ens med samme hos foregaaende Art, skjøndt den maaske er noget mindre slank. Hannen er endnu ubekjendt. Rygskjoldet er som hos ZV. hipes stærkt sammentrj^kt og viser, seet fra Siden, en temmelig regelmæssig oval Form, med den største Høide, der er noget større end den halve Længde, omtent paa Midten. De frie Kanter af Valvlerne er nedentil jevnt buede og danner helt fortil en stærk Krum- ning, inden de støder sammen ved Basis af Pande- pladen. Bagtil viser de sig skraat afskaarne i Ret- ningen forfra bagtil, og de nedre bagre Hjørner af Rygskjoldet danner derfor, som hos foregaaende Art, til hver Side en smalt afrundet Lap, der dækker Siderne af Bagkroppen og næsteu rækker til Begyn- delsen af Halen. Pandepladen (se Pl. IV, Fig. 9, 10) er vel udviklet og af meget smal tungedannet Form, temmelig stærkt hvælvet oventil, og forsynet i En- den med et spidst tornformigt Fremspring, der dai> ner Fortsættelsen af en langs den nedre Side lobende Kjøl. Sidste Bagkropssegment har, som hos fore- gaaende Art, et Par smaa afrundede Epimerer og er ligesom de 3 følgende Halesegmenter grovt sag- takket i den bagre Kant. Halegrenene er noget kortere end de 2 foregaaende Segmenter tilsammen, forøvrigt af fuldkommen samme Bygning som hos foregaaende Art. Øinene (se Pl. IV, Fig. 9, 11) udmærker sig i høi Grad ved sin ringe Størrelse og rudimentære Beskaffenhed, og rager kun lidet frem fra Rygskjol- det, hvorfor de let kan forbisees. De er, som hos N. hipes, dækkede oventil af en skjælformig, spidst udlobende Plade. Selve Øienstilken er af konisk recurved at the tip and furnished with long di- vergent plumose bristles; the epipodite with the dorsal lobe considerably larger than the ventral one. First pair of swimming feet with the ex- terior edge of the outer branch furnished only with 3 small teeth immediately above the 1st terminal spine. Caudal rami somewhat shorter than the 2 backmost segments taken together. Colour whitish, without pigmentation. Length of the animal 9 mm. Remarks. The species here spoken of is cer- tainly very nearly allied to the preceding one, but still is easily distinguishable from same by various well defined characteristics, of which may especially be noticed the rudimentaiy character of the eyes, and the shape and armature of the frontal plate. Also in the structure of the various appendages of the body, we may, on a closer comparison, be able to notice a number of smaller differences in the same from those of N. hipes. Description. The shape of the body of the female (see PI. I, fig. 4) agrees, on the whole, pretty exactly with that of the preceding species, althoixgh it is, perhaps, somewhat less slender. The male is yet unknown. The carapace is, as in N. hipes, strongly compressed and exhibits, viewed laterally, a pretty regular, oval form; with the greatest height, which is somewhat more than half the length, at about the middle. The free edges of the valves are evenly curved l)elow, and form, quite in front, a strong curvature until they unite at the base of the frontal plate. At the back they show them- selves obliquely truncated in a direction from back to front, and the lower posterior corners of the carapace form, therefore, as in the preceding species, on each side, a narrow rounded lobe which covers the sides of the metasome and extends almost to the commencement of the urosome. The fronlsil plate (see PI. IV, figs. 9, 10) is well developed and of very narrow linguiform shape, pretty strongly arched above, and furnished at the extremity with a pointed spiniform prominence which forms the contin- uation of a carnia that rans along the lower side. The last segment of the metasome has, as in the preceding species, a pair of small roimded epimera, and are, as well as the o succeeding caudal segments, coarsely serrated on the posterior edge. The caudal rami are somewhat shorter than the 2 preceding segments taken together, othei-wise of perfectly the same structure as in the preceding species. The eyes (see PI. IV, figs. 9, 11) distinguish themselves in a high degree by their small size and rudimentary character, and only project a little for- ward from tlie carapace; for which reason they may easily be overlooked. They are, as in N. hipes, covered above with a squamiform plate running 33 Form, uden nogen bemærkelig Opsvulmning i Enden. Af Pigment eller Syuselementer er der ikke det ringeste Spor at opdage. De ovre Folere (se Pl. IV, Fig. t)) er furholds- vis kortere end hos foregaaende Art, forovrigt af en meget lignende Bygning. Svoben er kun lidet læn- gere end Skaftet og kun sammensat af lU Led. Det skjælformige Appendix er derimod forholdsvis større end hos foregaaende Art, næsten halvt saa langt som Svøben, og af en mere aflang Form, forovrigt forsynet med en lignende kostformig Besætning af stive Børster. De nedre Folere (ibid.) stemmer idethele saa noie overens med samme hos foregaaende Art, at en nøiere Beskrivelse er iiuodvendig. Ogsaa Munddelene viser en meget lignende Byg- ning, skjondt enkelte mindre Differentser ved noiere Sammenligning lader sig paavise. Saaledes er Man- diblernes Palper (se Fig. 12) forholdsvis noget min- dre, og deres ildet Led har kun en enkelt meget stærk Boi'ste i den ydre Kant nær Spidsen. Forste Par Kjæver (Fig. 13) er ligeledes noget svagere ud- viklede, men forovrigt paa det nærmeste af samme Udseende som hos N. hipes. Paa 2det Par Kjæver (Figv 1-4) er Endognathens 2 Led kun ufuldkommeut sondrede og næsten af ens Længe; Exognathen er neppe mere end halvt saa lang og har et ringere Antal Randborster end hos N. hipes. Branchialfodderne (Fig. 15, 16) udmærker sig navnlig ved Endopoditens Længde og Tyndhed. Paa de forreste Par overrager den betydeligt Exopoditen og har sidste Led stærkt omboiet samt besat med særdeles' lange divergerende Fjærbjorster. Exopo- diten er af skjævt oval Form og forsynet med flere Randbørster, hvoraf de yderste er tydeligt cilierede. EpipcMlÅten har paa alle Par den dorsale Lap be- tydelig 'mindre end den ventrale, medens det om- vendte var Tilfældet hos foregaaende Art. Som hos denne, bemærkes nogen Forskjel i de forskjellige Hoveddeles indbyrdes Forhold paa de forskjellige Par Branchialfodder. Sidste Par (Fig. 16) har saa- ledes et fra Iste Par (Fig. 15) temmelig afvigende Udseende og skiller sig ogsaa kjendeligt fra det tik svarende hos N. hipes (Pl. III, Fig. 6). Endopoditen er her, i Modsætning til hvad Tilfældet er med de ovrige Par, meget kort og uden nogen tydelig Led- deling, og Exopoditen er ligeledes forholdsvis min- dre end hos N. hipes og i Yderkanten forsynet med en Rad af cilierede Børster. Fem lignende Fjær- borster findes ogsaa paa den korte og tilrundede ventrale Lap af Epipoditen. Svommefodderne forholder sig i alt væsentligt som hos i\^. hipes; kun er de idethele af en noget ^ — G. 0, Sårs: Fauna Xoyv€(]ia:. OTit to a point. The ocular stem itself is of conical shape, without any noticeable swelling at the ex- tremity. There is not the slightest trace of pigment or visual elements to be discovered. The superior antennæ (see PI. IV, fig. 9) are rela- tivelj' shorter than in the preceding species, other- wise of a very similar structure. The flagellum is only a little longer than the peduncle and is composed of only 10 joints. The squamiform appendage is, on the contrary, relatively larger than in the preceding species, almost half the length of the flagellum and more oblong in form, otherwise furnished with a similar supply of stiff l)ristles. The inferior antennæ (ibid.) agree, upon the whole, so exactly with those of the preceding species that a more detailed description is unnecessary. The oral parts also exhibit a verj^ similar struc- ture, although upon a closer comparison a few small divergencies maj' be observed. Thus the palpi of the mandibles (see fig. 12) are relatively some- what smaller, and their 2nd joint has only a single, very strong bristle on the outer edge, near the tip. The first pair of maxillæ (fig. 13) are likewise some- what more faintly developed; but otherwise pretty nearly of the samme appearance as in A. hipes. In the 2n(l pair of maxillæ the 2 joints of the endo- gnath are only imperfectly separated and almost equal in length ; the exognath is scarcely more than half as long, and has a smaller number of marginal bristles than in N. hipes. The l)ranchial feet (fig. 15, 16) especiallj^ dis- tinguish themselves by the length and slenderness of the endopodite. In the foremost pairs it considerably overreaches the exopodite, and has the terminal joint strongly recurved, and also beset with parti- cularly long, diverging plumose bristles. The exo- podite is of oblique, oval form, and furnished with several marginal bristles, of which the outermost are distinctly ciliated. The epipodite has, in all pairs, the dorsal lobe considerably smaller than the ventral one, whilst the opposite was the case in the preceding species. As in that, there is observed some difference in the mutual relations of the various chief parts of the different pairs of the branchial feet. The last pair (fig. 16) have thus a pretty divergent appearance from the 1st pair (fig. 15), and distinguish themselves perceptibly from the corres- ponding pair in N. hipes (21. Ill, fig. 6). The endo- podite is here, in contrast to what is the case in the other pairs, very short, and without any distinct articular division; and the exopodite is likewise relatively smaller than in X. hipes, and is furnished on the outer edge with a series of ciliated bristles. Five similar plumose bristles are also found on the short and rounded ventral lobe of the epip(jdite. The swimming feet have, in all essential respects, the same structure as in N. hipes; only that they 34 mere smækker Form. Paa Iste Par (Fig. 17) er der dog den Forskjel, at Yderkanten af den ydre Gren kun har, umiddelbart ovenfor den yderste Torn^ 3 Smaapigge, medens hos N. hipes hele denne Kant er tæt og regelmæssigt pigget. De 2 Par rudimentære Halefødder (Fig. 18, 19) viser ligeledes et Udseende, meget nær overens- stemmende med samme hos denne Art, alene med den Forskjel, at Tornernes Antal paa begge er noget ringere. Farven er hos det levende Dyr hvidagtig, uden nogen bemærkelig Pigmentering. Integuraenterne er tynde og gjennemsigtige, saa de indre Organer tem- melig tydeligt skinner igjennem. Æggene i Klækkehulen er forholdsvis store og af en meget bleg gulagtig Farve. Længden af den ægbærende Hun er kun 9 mm., Størrelsen er altsaa betydelig ringere en hos iV. bipes. Forekomst. Jeg har hidtil kun seet 3 Exjil. af denne Art, alle Hunner. De blev tagne til forskjel- lige Tider paa 3 vidt adskilte Punkter af vor Kyst, det ene ved Hvitingso, udenfor Stavanger, det 2det i Trondhjemsf jorden, og det 3die ved Lofoten. Ex- emplarerne forekom paa alle 3 Steder i et Dyb af fra 150 — 200 Favne og paa blod Lerbund. Arten synes herefter at maatte betragtes som en tidpræget Dybvandsform, hvad der ogsaa kan sluttes ■ af de ufuldkomment udviklede Synsredskaber. Udenfor Norge er den endnu ikke bleven observeret. are altogether of a somewhat more slender form. In the 1st pair (fig. 17) there is, however, the diffe- rence, that the outer edge of the outer branch has, immediately above the outermost spine, only 3 small spikes, whilst in N. hipes the whole of that edge is closely and regularl}' spiked. The 2 pairs of rudimentary caudal feet (figs. IS, 19) likewise present an appearance very nearly correspondent with those in that species, with the difference only, that the number of spines on both is somewhat smaller. The colour in the living state of the animal is whitish, without any noticeable pigmentation. Tlie integuments are thin and transparent, so that the internal organs are pretty distinctly visible through them. The ova in the hatching cavity are relatively large, and of a very pale j^ellowish colour. The length of the ovigerous female is only 9 mm. The size is thus considerably less than in N. bijies. Distribution. I have hitherto only seen 3 spe- cimens of this species, all females. They were taken at different times, at 3 widely separated places off our coast; the one at Hvitingso, off Stavanger, the 2nd in the Trondhjem.sfjord, and the 3rd at the Lo- foten isles. The specimens were obtained, at all the 3 places, at a depth of from 150 — 200 fathoms and on soft claj'^ bottom. It appears from this, that the species must be considered as a distinguished deep- water form, which may also be gathered from the imperfectly developed visual apparatus. Out of Nor- way it has not hitherto been observed. Subordo II. PHYLLOPODA. Character. Branchiopoder af meget foi'skjellig Kropsform, dels uden, dels med Rygskjold, det sidste undertiden ndviklet i Form af 2 voluminose, det hele Dyr omsluttende Valvler. Legemets Segmenta- tion forskjellig hos de forskjellige Former. Øinene dels stilkede, dels sessile, undertiden næsten sammensmel- tede; et mediant Enkeltoie ^ocellus) tilstede. Folerne i Regelen meget ulige ndviklede; Iste Par som oftest meget smaa og udelukkende sensitive; 2det Par af forskjellig Bygning, snart rudimentære (hos det voxne Dyr), snart udviklede til kraftige 2grenede Aarer, eller til tangformige Griberedskaber (hos Hannen). Dverlæben vel udviklet, klapformig; Under- læben i Regelen manglende. Kindbakkerne hos det udviklede Dyr uden Palpe. To Par Kjæver tilstede, begge smaa og af forholdsvis simpel Bygning. Alle bag Munddelene folgende Lemmer respiratoriske, af tilnærmelsesvis uniform Bygning og bladdannet lap- pet Form; deres Tal meget forskjelligt, undertiden abnormt stort. Ud vikl ingen i Regelen en compli- ceret Metamorphose, begyndende med et frit Nauplius- Stadium. Indlandsdyr. Bemærkninger. Denne Underorden omfatter et ikke meget stort Antal Dj-reformer, der imidlertid viser meget væsentlige Forskjelligheder, saavel hvad det jalre Udseende som den indre B3rgning angaar. Hvad der hovedsageligt characteriserer denne Af- deling af Branchiopoder, og har givet dem sit Navn, er Structuren af de bag Munddelene folgende Lem- mer, der alle viser et lignende bladformigt og lappet Udseende som de til Midtkroppen hos Phyllocariderne horende saakaldte Branchialfodder. Da de tillige i sin Function er udpræget respiratoriske, benævnes Sudordo II. PHYLLOPODA. Characters. Branehiopods of very various shape, partly without and partly with carapace, the lastnamed sometimes developed in the form of 2 voluminous valves enveloping the entire animal. The segmentation of the body different in the various forms. Eyes partly pedunculated, partly sessile, sometimes nearly coalescent; a median single eye (ocellus) present. Antennae, as a rule, very iinequally developed; 1st ]iair most frequently very- small and exclusivel}' sensitory; 2nd pair of vari- able structure, sometimes rudimentary (in the adult animal), sometimes developed to powerful, 2-branched oars, or to pincer-shaped prehensile ajiparatus (in the male). Anterior lip well developed, flap-formed; posterior lip, as a rule, wanting. Mandibles, in the developed animal devoid of palpi. Two pairs of max- illae ]iresent, both small and of relatively simple structure. All the appendages placed behind the oral parts respiratory, of ap])roximately uniform structure and leaf-formed shape; their number very variable, sometimes abnormally large. The de- velopment iTsually a complicated metamorphosis, commencing with a free Nauplius-stage. Inland animals. Remarks. This sub-order includes a not very large number of animal forms, which exhibit, how- ever, very material divergencies, both in respect of the external appearance as well as in the internal structure. What chiefly characterizes this division of Branchio])ods and has gevin to it its designation is, the structure of the appendages placed behind the oral parts, which all exhibit a similar leaf-shaped and lobed appearance as the so-called branchial-feet pertaining to the mesosome in the Phyllocarida. As they are, besides, in their function prominently 36 de ogsaa Ler paa samme Maade. Foi-skjellen er altsaa, at her alle lia^^Munddelene følgende Lemmer er ægte Branchialfodder, medens dette hos Phyllo- cariderne kun er Tilfældet med en Del af dem. I Følernes Bygning er der saa stor Forskjel hos de forskjellige Former, at intet andet bestemt fælles Charactertræk kan anføres end, at det Iste Par ude- lukkende er sensitive og derfor af en meget tander Structur. Ogsaa Øinenes Bygning er meget forskjel- lig, idet de snart er stilkede som hos Phyllocariderne. snart sessile, snart sammensmeltede til et enkelt i det indre af Hovedet beliggende Organ. Characte- ristisk ligeoverfor Phyllocariderne er Tilstedeværel- sen af et mediant Enkeltoie (ocellus). Angaaende Munddelenes Structur, kan fremhæves Mangelen af Palper paa Kindbakkerne, og den forholdsvis simple Bygning af de 2 Par Kjæver. De hidtil Lekj endte Phyllopoder vil passende kunne fordeles paa 3 større Afdelinger, for hvilke jeg allerede i 1867') har foreslaaet følgende Benæv- nelser: Anosfraca, Notostraca og Conchostraca. For- skjellen mellem disse Afdelinger er saa stor og gjen- nemgribende, at de ikke, som af de fleste Forskere gjort, kan opfattes som blotte Familier, men ube- tinget bør tillægges en langt høiere S3'stematisk Værdi (Tribus eller Sectioner). Til enhver af disse Grupper hører et meget begrændset Antal af Slæg- ter, som delvis lader sig fordele paa flere Familier. De berhen hørende Slægttypers Faatallighed og i Regelen overordentlig skarpt u.dprægede For- skjel, i Forbindelse med deres sporadiske Forekomst paa vidt adskilte Localiteter, synes at tyde hen paa, at vi i Phyllopoderne har de sidste divergerende Grrene af en uddøende Dyrgruppe, som i-imeligvis, at dømme efter flere palæontologiske Fund, har været langt rigere repræsenteret i tidligere Jordperioder. Ogsaa af disse Dyrs Organisation og Ud vikling synes man at være berettiget til at slutte, at de maa være af meget gammel Oprindelse. Det yderlig variable Antal af Kropssegmenter og af Lemmer, disse sid- stes uniforme Bygning, den oftest kun lidet skarpt udprægede Sondring af Legemet i tydeligt begrænd- sede Kro])safsnit, alt dette er Characterer, der aaben- bart henpeger paa primitive Tilstande, hvori endnu ikke de hos do moderne Crustacegrujjper gjældende Forhold rigtigt har fixeret sig. Phyllopoderne min- der i denne Henseende ikke saa lidet om de æld- gande Trilol)it(!r, ligesom der ialfald hos Afdelingen Notostraca er en umiskj endelig habitnel Lighed med de ligeledes langt op i den geologiske Tid gaaende respiratory, they are also named here in the same manner. The difference, therefore, is, that here all the appendages placed behind the oral parts are real branchial feet, -while in the Plijdlocarida that is only the case with a part of them. In the structure of the antennæ there is such a great ditter- ence in the various forms, that no other certain characteristic feature in common can be given, than that the 1st pair are exclusively sensitory and there- fore of a very delicate structure. The structure of the eyes also is . veiy different, as they are some- times pedunculated, as in the Phyllocarida, sometimes sessile, sometimes coalescent to a single-organ situ- ated in the interior of the head. The presence of a single median eye (ocellus) is a characteristic feature in contrast with the Phyllocarida. Re- garding the structure of the oral parts may be mentioned, the absence of palpi on the mandibles, and the relatively simple structure of the 2 pairs of niaxillæ. The Phyllopods hitherto known may siiitably be assigned to 3 large divisions, for which the author, as early as 1867^), proposed the following designations: Anosfracn, Notostraca and Conchostraca. The differ- ence between those divisions is throughout, so great, that they cannot be regarded as families only, as has been done by most writers, bi;t ought, evid- ently, to be assigned a far higher systematic value (Tribus or Sections). To each of these groiTps there pertain a very limited number of genera, which to some extent may be referred to several families. The paucity in number of the generic types pertaining hereto, and the, as a rule, extraordinarily sharply distinguished difference, in connection with their sporadic occurrence in widely separated loca- lities, seems to give an indication that in the Phyllo- pods we have the last diverging branches of a van- ishing animal group, which, probably, judging by several palæontological discoveries, has been far more abundantly represented in earlier periods of our earth's history. From the organisation and develop- ment, also, of these animals, it seems as if we were warranted in concluding that tliey must be of very old origin. The extremely variable niimber of body segments and of appendages; the uniform structure of the last-named; the usually only little sharply distinguished separation of the bod}^ in distinctly defined divisions, are all characteristics that evid- ently point to primitive conditions, in which the regulating relations of the modern gi'oups of (;ru- staceans had not yet been thoroughly consolidated. The Phyllopods remind us in that respect, not so little of the ancient Trilobites, while, also, there, in ') G. O. Sar.s, Hietoiro naturelle des (Jrnstacés d'cau douce de Norvége, I. ') G. O. Sars, Histoirc naturelle des Criistact's d'eau douce de Norvege, I. 37 Dolkiialer (Xiphosura). Det synes altsaa som om disse Dyr, nagtet deres Organisation idethele bar naaet et forholdsvis meget boit Udviklingstrin, dog ved Siden beraf bar conserveret flere af de primitive Cbaracterer, der maa antages at bave udmærket de ældgamle Stamformer, bvorfra alle de moderne Cru- staceer i sidste Instans bar tåget sit Udspring. Ogsaa Udviklingen synes at stotte denne baade af Prof Claus og Dr. Dobrn fremboldte Anskuelse. Saagodtsom bos alle Pbyllopoder begynder nemlig den frie Udvikling med det overordentlig simple saakaldte Nau])lius Stadium, og Larven gjennemgaar derpaa en Række af successive (Jmformuinger, der lidt efter lidt forbereder Pb^dlopodestadiet. Det bor dog ber bemærkes, at Dr. Packard i sit fortjeust- fulde Værk over Nordamerika's Pbyllopuder bævder en berfra meget forskjellig Anskuelse. Efter denne Naturforskers Mening er Pbyllopoderue tværtimod af meget ny Oprindelse og frenistaaet ved en videre Udvikling af Cladocer-Tj^pen. Dette kunde maaske til Nød lade sig bore, bvor der er Sporgsmaal om den ene af Pbyllopodernes H Sectioner, de saakaldte Concbostraca, der ganske sikkert viser en meget ud- præget Affinitet til Cladocererne. Men langt van- skeligere bliver det at faa udledet de 2 ovrige Pbyl- lopode-Typer fra Cladocererne. Der gives ikke en eneste Cladocer, der viser den fjerneste Tilnærmelse til de for Grupperne Anostrac;i og Notostraca cba- racteristiske Eiendommeligbeder, og det gaar heller ikke an, at aflede disse 2 Typer fra den 3die Con- cbostraca. De 3 Pbyllopodetyper staar i Virkelig- heden paa en Maade belt isolerede og bar rimelig- vis et meget forskjelligt Udspring. Langt natur- ligere end den af Packard fremsatte Hypothese om Pbyllopodernes Afstamning fra Cladocererne, synes det mig at være at vende Sagen helt om, og altsaa antage, at Cladocererne er af yngre Oprindelse end Phyllopoderne og bar udviklet sig som en Sidegren fra Gruppen Concbostraca. Raadsperger vi Palæ- ontologien, vil ialfabl intet Modbevis mod en saadan Antagelse kunne hentes berfra; tværtimod. Medens man nemlig endnu ikke kjender en eneste Cladocer i fossil Tilstand, finder man talrige fossile Skaller af utvivlsomme concbostrake Pliyllopoder, nærmest benborende til Slægten Esllierkt. lige op til den De- voniske Periode; noget der jo viser, at ialfald denne Gruppe af Pbyllnpoder ikke kan være af saa ny Oprindelse, som man efter Packai'ds Hypothese synes at maatte antage. Nu er der forskjellige morpbo- logiske Forhold, der gjor det hoist usandsynligt at antage, at Gruppen Concbostraca skiilde repræsen- tere de ældste og oprindeligste Pbyllopoder. Vi kommer ad denne Vei snarere til en stik modsat Slutning, nemlig at denne Gruppe er af en betyde- lig yngre Oprindelse end de 2 ovrige. At man ikke kjender nogen for verdenske Former af disse sidste Grupper, kan naturligt forklares af de barben bo- the division Notostraca, at any rate, is an unmistak- able habitual resemblance with the sword-tails (Xi- phosura), likewise passing far back in geological times It appears therefore, as if these animals, although their organisation has, upon the whole, attained, relatively, a very high stage of develop- ment, still bave retained several of the primitive characteristics which must be assumed to have distinguished the ancient ancestors, from which all the modern crustaceans have finalh' bad their origin. The development also seems to support that view, advocated both by Prof. Claus and Dr. Dobrn. In almost all the Phyllopods the free development begins, namely, with the extraordi- narily simple so-called Nauplius stage; and the larva thereupon iTudergoes a series of successive transformations, which, little by little, prepare the pbyllopod-stage. It ought to be noted here, how- ever, that Dr. Packard in his admirable work upon the Phyllopods of North America, maintains a very different view. According to the opinion of that naturalist, the Phyllopods are, on the con- trary, of very late origin, and produced by a further development of the Cladocera-type. That might per- haps, in the absence of anj^tbing better, be accepted, when tbe question concerns one of the 3 sections of Phyllopods, tbe so-called Concbostraca, which ijuite certainly exhibits a very distinguished affinity to tbe Cladocera. But far more difficult does it become, to trace the 2 other phyllopod-types from the Cla- docera. There is not a single Cladoceran that exhi- bits the slightest approximation to tbe characteristics peculiar to the groups Anostraca and Notostraca, and neither is it permitted for its to trace these 2 types from tbe 3rd, tbe Concbostraca. Tbe 3 types of Phyllopods stand in reality, in a measure, quite isolated, and probabh' have a very different origin. Far more natural than tbe hypothesis of tbe deri- vation of the Phj'llopods from tbe Cladocera, pre- sented b}' Packard, does it appear, to me, to be, to quite reverse the case, and consequentlj^ assume that the Cladocera are of later origin than tbe Phyllo- pods and bave become developed, as a lateral branch, from tbe group Concbostraca. If we consult palæ- ontology, we will, at any rate, find no testimony rebutting such an assumption to be obtained there- from ; on tbe contrary, while we do not yet know of a single Cladoceran in fossil condition, we find numerous fossil remains of indubitable concbostracan Phyllopods most closely approaching to tbe genus Estherin, even up to the Devonian period; a fact that certainly shows that that group of Phyllopods, at any rate, cannot lie of such late origin as we, according to Packard's hy])otbesis, seem obliged to suppose. Now there are various morphological rela- tions that make it extremely improbable to suppose that the group (.-onchostraca represents the oldest 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. d'.} Sectio I. Anostraea. (Nøgne Phjllopoder). Syn : Phyllopoda pisciforinia. Sectio I. Anostraea. (Naked Phyllopods). Syn: Phyllopoda pisciformia. Character. Legemet forlænget, meget blodt og bøieligt, mere eller mindre ormformigt, nden Spor af noget Rygskjold eller Skal. Legemets Segmen- tering temmelig uniform, dog med tydelig Adski Helse i Hoved, Midtkrop og Hale. Øinene tydeligt stilkede og bevægelige, af en lignende Bygning s(im lios Ne- balia. Forste Par Folere meget smaa, traadformige; 2detPar hos Hunnen mere eller mindre riidimentære. fligformige, hos Hannen omdannede til kloformige Grriberedskaber. Kindbakkerne med stump riflet Tj'ggeflade, nden tydeligeTænder. Branchialfødderne uden Coxallap, men med 1 eller 2 Dækblade ved Basis paa den ydre Side, alle af noget nær ens Byg- ning, udpræget respiratoriske, men samtidigt og§aa loconiotoriske. Halen uden Lemmer, dens forreste Segmenter delvis sammenvoxne og givende Udspring for de ydre Kjonsvedhæng: hos Hunnen en enkelt- mere eller mindre sækformig Ægbeholder med ter- minal Aabning, hos Hannen 2 fuldstændig skilte og meget smaa Copulationsredskaber. Udviklingen en compliceret Metamorphose begyndende med et frit Nauplius-Stadium. Bemærkninger. De til denne Afdeling horende Phyllopoder er let kjendelige ved sit langstrakte og bløde, næsten ormlignende Legeme, ved Mangelen af et Rygskjold eller Skal, ved de tydeligt stilkede Øine, ved den eiendommelige Bygning af 2det Par Folere hos de to Kjøn, endelig ved den eiendomme- lige Beakaifenhed af de ydi-e Kjonsvedhæng. Man kan fordele de hidtil bekjendte Former paa 3 Fa- milier: Branchipodidæ, TliamnocephaJidæ og Polyarte- miidæ. Kun den forste og sidste af disse Familier er repræsenterede i Norges Fauna. Den 3die Fa- milie er opstillet af Packard for en mærkelig nord- amerikansk Form, Tliamnocephalus platyurus Packard, der, foruden ved de eiendommelige Frontalvedhæng, udmærker sig i hoi Grrad derved, at Halen ender med en enkelt bred horizontal Svommeplade. Characters. Body ])rolonged, very soft and flexible, more or less vermiform, without trace of any carapace or shell. The segmentation of the body pretty uniform, but with distinct division lie- tween the head, the mesosome and the tail. Eyes distinctly pedunculated and moveable, of similar structure to these in Nehalia. First pair of antennæ verj' small, filiform. Second ])air more or less rudi- mentary in the female, flap-shai)ed; transformed in the male to claw-formed prehensile apparatus. Mandibles with lilunt rifled masticatory surface, with- out distinct teeth. Branchial feet without coxal lobe, but with one or two covering plates at the base on the outer side; all of somewhat uniform structure, distinguished respiratory, Imt at same time also locomotive. Tail without appendages; the foremost segments partly coalescent and furnishing the origin for the oiiter sexual appendages : in the female a single, more or less sac-formed marsupium with terminal aperture; in the male 2 completely separated and very small copulative appendages. The development a comjdicated metamorphosis, com- mencing with a free Nauplius stage. Remarks. The Phyllopods belonging to this division are easily recognizable by their elongate and soft, almost vermiform body, by the absence of a carapace or shell, by the distinctly pedunculated eyes, by the peculiar structxire of tlie 2nd pair of antennæ in the two sexes and, finally, by the pe- culiar character of the outer sexual appendages. We may refer the hitherto known forms to 3 families: Branchipodidtf, TliamnocephaJid(e and Polyartemiidæ. Only the first and last named of these families are repre.sented in the fauna of Norway. The 3rd family is established by Packard, to include a remarkable North American form, ThamnocepJiaJus platijurus. Packard, which, besides by its peculiar frontal appendages, distinguishes itself in a high degree, in that the tail terminates in a single, broad hori- zontal swimming plate. 40 Fam. 1. Branchipodidæ. Fam. I. Branchipodidæ. Character. Legemet smalt cylindriskt, noget tykkere fortil, med Halen vel udviklet og tydeligt segmenteret hos begge Kjon, endende med 2 bøi^ste- besatte Halegrene. Hannens Gribeantenner tydeligt segmenterede og i Regelen forsynede med en rudi- mentære Bigren. Frontal vedliæng tilstede hos Han- nen eller manglende. 11 Par Branchialfodder til- stede, alle med en enkelt sagtakket ydre Dækplade. Hannens Ægbeholder tydeligt sækformig og bagud- rettet, udspringende fra de 2 forreste Halesegmenter. Bemærkninger. Til denne Familie hører ialt 5 Slægter, nemlig; Artemia Leach, Branch/necki, Verrill, Branchipus SchafFer, Ckirocephalus Prevost og Streptocephalus Baird. Kun en af disse Slægter, Brancliinedu, er repræsenteret i vor Fauna. Fami- lien er hovedsageligt characteriseret ligeoverfor den følgende Familie, Pohjartemiiflæ, ved den forskjellige Bygning af Hannens Gribeantenner, ved det Iiety- delig ringere Antal Branchialfodder, ved Halens Form, endelig ved BeskatFenheden af Hunnens Ægge" beholder. Fra Familien Tamnoceplialieholder, endelig ved betydelig kortere Halegrene. Betydelig storre Affinitet liar den til Slægten Artrmia Leach, med hvilken den stemmer overens baade i Henseende til den almindelige- Habitus og ved Mangelen af Frontal- vedhæng hos Hannen. Den skiller sig imidlertid ogsaa fra denne Slægt ved visse vel iidprægede Cha- racterer, saaledes ved den forskjellige Form af Han- nens Gribeantenner og af Hunnens Ægbeholder, endelig derved, at Halen har et Segment flere. Man kj ender ialt med Sikkerhed 0 herhen horende Arter, nemlig, foruden den nedenfor nærmere beskrevne arktiske Form, 2 nordamerikanske Arter: B. colora- densis Packard og B. Lindahli Packard, en af Baird fra Jerusalem beskreven Form, B. cxhnia, og to russiske Arter fra Omegnen af Odessa, B. sphiosa M. Edw. og B. ferox M. Edw. Det var denne sidste Art, som den russiske Naturforsker Schmankewitch troede at se forvandlet til en Arteniia ved paa kiin- stig Maade at domesticeres i saltholdigt Vand, noget der vel egentlig er at forståa saaledes, at Arten under de forandrede Forhold antog visse Charac- terer, der mindede om ovennævnte Slægt. Brancliinecta paliidosa (Muller). (Pl. VI, VII, VIII), Cancer stagnalis, Fabr., Fauna gvonlandica, No. 224 (non Linné). Brancliipus paludoaus, JMiiller, Zool. Danica II, 10, Pl. 48, Fig. 1—8. Braiiclupus viiddciidorfianns, Fi.scher, Middendorf s Sibirisohe Reisen, Bd. II, p. 163, PI. VII, Fig. 17—23. Branchhiccta gronlandica, Verrill, Amer. Journ. fgc. 1869, p. 253. Branchinccta arctirn, Idem, ibid. Artscharacteristik. Legemets Form slank og elegant, med de 3 Kropsafsuit vel markerede. Ho- vedet af middelmaadig Størrelse, jevnt afrundet for- til hos begge Kjøn. Halen betydelig længere end den foranliggende Del af Legemet, smalt cj'lindrisk, med næstsidste Segment det længste, og sidste Seg- ment omtrent halvt saa langt. Halegrenene næsten dobbelt saa lange som sidste Segment, smalt lancet- formige og tæt kantede med cilierede Borster. 2det Par Folere hos Hunnen næsten af Hovedets Længde, meget skraat afskaarne i Enden, med det bagre Hjorne udtrukket i en skarp Spids. Samme Følere hos Hannen mere end dobbelt saa lange, Skaftet noget krummet ved Basis, tykt cylindriskt, med en E,ad af smaa Tænder langs den indre Kant; Ende- delen lidt kortere, noget boiet paa Midten og jevnt afsmalnende mod Spidsen, som er stumpt tilrundet. Branchialfodderne med Endopoditens ydre Lap hos 6 — G. 0, Sårs; Fauna Xorvegiic. by the absence of frontal appendages in the male, by the verj' different shape of the marsupium of the female, and, iinally, by considerably shorter caudal rami. It has much greater affinity to the genus Artemia, Leach, with which it agrees, both in regard to the general habitus and in the absence of frontal appendages in the male. It distinguishes itself, how- ever, also from that genus by certain well marked characteristics; thus, by the different form of the prehensile antennæ of the male and of the mar- supium in the female, and, finally, in the tail hav- ing an additional segment. "We know with certainty of (J species, altogether, pertaining hereto, namelj', besides the Arctic form more particularly described below, 2 North American species ; B. coJoradensis, Packard, and B. LindaJdi, Packard; a form from Jerusalem, described by Baird, B. eximia; and 2 Russian species from the neighbourhood of Odessa, B. spinosa, M. Edw. and B. ferox M. Edw. It was the last named species that the Russian naturalist Schmankewitch believed to have seen transformed to an Arlemia, by being, in an artificial manner, do- mesticated in water containing salt; a fact which may be more properly understood in this manner, viz. — that the species, under the changed relations, assumed certain characters which reminded of the above-named genus. Branehinecta i>alii(losa (Milller). (PI. VI, VII, VIII). Cancer sfac/nalis, Fabr., Fauna gronlandica. No. 224 (non Linné). BrancMpHS pnludosus, Mliller, Zool. Danica U, 10, PI. 48, figs 1—8, Bra>icJiipi(s middcndorfianits, Fischer, Middendorf' s Sibirische Reisen. Bd. II, p. 163, PI. VII, flgs. 17—23. Branehinecta gronlandica, Verrill, Amer. Journ, Sc, 18C9, ii. 263. Branehinecta arctica, Idem, ibid. Specific characteristics. Form of body slender and elegant, with the o body-divisions well mar- ked off. Head of moderate size, evenlj' rounded in front in both sexes. Tail considerably longer than the part of the body lying in front of it, narrow cylindrical, with the penultimate segment the longest, and tiie last segment about half as long. Caudal rami almost twice as long as the last segment, narrow lanceolate in shape, and closely edged with ciliated bristles. Second pair of an- tennæ, in female, almost the length of the head, very obliquely truncated at tlie extremity, with the posterior corner drawn out to a shai'p point. Same antennæ in male more than twice as long; shaft somewhat curved at the base, thick cylindrical, with a series of small teeth along the inner" edge; terminal part a. little shorter, somewhat curved in the middle, and narrowing evenly towards the point. 42 Hunnen kort triangulær, lios Hannen betydelig stær- kere uddraget og næsten leformig indadkrummet. Hunnens Ægbeholder særdeles forlænget, rækkende næsten til Enden af næstsidste Halesegment. Han- nens ydre Kjønsvedhæng cylindriske, forsynede ved Basis fortil med 2 fremsjjringende Flige, mellem hvilke der er en dyb Indbugtning. Legemet hos begge Kjøn gjennemsigtigt, med et mere eller min- dre tydeligt gronligt eller rodligt Anstrog. Hun- nens Længde indtil 18 mm., Hannens 23 mm. Bemærkninger. Denne Art er allerede i 1780 af 0. Fabricius anført fra Grønland, men urigtigt identificeret med Br. siagnalis Schæffer. Senere er den under den oventor anførte Species-Benævnelse kjende- ligt beskrevet og afbildet af 0. Fr. Muller i hans bekj endte Værk, Fauna danica. De af Prof. Verrill som B. grønlandica og ardica opførte Former har senere vist sig at være identiske med nærværende Art, og det samme er utvivlsomt ogsaa Tilfældet med B. mlddendorfianus Fischer, Af de 2 nordame- rikanske Arter beskrevne af Packard, synes B. colo- radensis at komme meget nær den her omhandlede Art, medens B. Lindahli skiller sig mere kjendeligt, navnlig A^ed de betydelig stærkere forlængede Hale- grene. General Beskrivelse. Legemet er hos begge Kjon (se Pl. VI, Fig. 1 — 4) smalt og forlænget, næ- sten ormformigt, med særdeles tynde og boielige Litegnmenter, samt inddelt i tydelige Segmenter. Man kan adskille 3 temmelig skarpt begrændsede Kropsafsnit, nemlig Hoved, Midtkrop og Bagkrop eller Hale. Hovedet bestaar igjen af 2 Partier, et forreste og et bagerste, skilte ved en tydelig over Rygsiden gaaende Tværsutur. Det forreste Parti er noget opsvulmet, næsten kugleformigt, og mere eller min- dre stærkt nedboiet. Det bærer Øinene og 2 Par Feiere, samt fortsætter sig nedentil i Overlæben. Til det bagre Parti eller Nakkedelen horer de øvrige Munddele. Af di.sse er mest ioinefaldende de kraf- tigt udviklede Kindbakker, der som et Par Bøiler omgiver Hovedet paa Grændsen mellem dettes 2 Af- snit, og hvis baadformige Corpora danner til hver Side et tydeligt convext Fremspring, selv bemærke- ligt, naar Dyret sees ovenfra. Lige bag Kind- bakkerne sees til hver Side af Nakkesegmentet en S-formigt bugtet Figur, den saakaldte Skalkjærtel, hvis bagre Del omsluttes af en lidt fremspringende Hudfold, den første svage Antydning til det hos andre Phyllopoder saa stærkt udviklede Rygskjold eller Skal. Ventralt udgaar fra Nakkesegmentet de 2 Par Kjæver. which is bluntly rounded. Branchial feet with the outer lobe of the endopodite, in female, short tri- angular; in male considerably more drawn out, and almost falciformly curved inwards. Mar- supiiim of female greatly prolonged, reaching al- most to the extremity of the penultimate caudal segment. Outer sexual appendages of male cylin- drical, furnished in front, at the base, with 2 projecting flaps, between which there is a deep sinus. Body transparent in both sexes, with a more or less distinct greenish or reddisji tinge. Length of female up to 18 m. m.; that of male 23 m. m. Remarks. Tliis species is, as early as 1780, recorded by A. Fabricius from Greenland, but errone- ously identified with Bt. sfngnalis, Schæffer. Subse- quently it has been, iinder the above-named specific designation, recognizably described and illustrated by 0. Fr. Muller in his well-known work. Fauna danica. The forms established as B. gronlandica and arcfica by Prof. Verrill, have subsequently shown themselves to be identical with the present species, and the same is also indubitably the case with B. middendorfianns, Fischer. Of the 2 North Ame- rican species described by Packard, B. coloradensis appears to approach pretty closely the species here described, whilst 7?. i/«f7a/i?«' distinguishes itself more noticeabl}', especiall_y bj' the considerablj' more prolonged caudal rami. General description. The body is, in both sexes, (see PI. VI, figs. 1 — 4) narrow and prolonged, almost vermiform, with particularl}' thin and flexible inte- guments, and is divided into distinct segments. We can distinguish 3 pretty sharply defined divi- sions of the body, viz., the cephalon, the mesosome, and the metasome or tail. The cephalon, again, consists of 2 parts, an an- tei'ior and a posterior one, separated by a distinct transversal suture passing across the dorsal side. The foremost part is somewhat swollen, almost glo- bular, and more or less strongly bent downwards. It carries the e^^es and the 2 pairs of antennæ, and is continued downwards in the upper lip. The other oral parts pertain to the posterior, or cervical part. Of these, the most striking are the powerfully de- veloped mandibles, which like a pair of bows sur- round the head on the limit between its 2 divisions, and whose cymbiform corpora form on either side a distinctly convex prominence, even noticeable when the animal is viewed from above. Just beliind the mandibles there is seen, on either side of the cervi- cal segment, an S-formed flexuous figure, the so-called shell-gland, whose posterior part is enclosed b\' a slightly projecting integumental fold, the first faint indication of the, in otiier Phyllopods so strongly developed carapace or shell. Tlie 2 pairs of 43 Det paa Hovedet følgende Kropsafsnit, Midt- kroppen eller Truncus, er fortil omtrent af Hovedets Brede og lidt nedtrykt, men afsmalnes lidt i sin bagersteDel. Det er sammensat af 11 paa hinanden følgende korte og ensformigt udviklede Segmenter, hvoraf ethvert bærer et Par Branchialfodder. Disse sidste folger med regelmæssige korte Mellemriim efter liinanden, dannende med sine forskjellige Lap- per og talrige Børster til liver Side en bred Bræmme. Herved fremkommer langs Midtkroppens Underside en af samtlige Branchialfodder begrændset kanal- agtig Fordybning, der gradvis tiltager noget i Brede fortil, hvor den stoder op mod Mundregiouen. Bagkroppeu eller Halen er overordentlig slank, betydelig smalere end Midtkroppen, og af regelmæs- sig cylindrisk Form. Den udgjør kjendeligt mere end Halvdelen af Legemets Totallængde, og er sam- mensat af 9 Segmenter foruden Halegrenene. Af disse Segmenter er de '2 forreste kun i den dorsale Del tydeligt sondrede, medens de ventralt gaar over i hinanden og danner her Udspringet for de ydre Kjonsvedhæng. Disse 2 forste Segmenter af Halen vil derfor passende kunne benævnes: < Kjønsringene». Hos Hunnen er det forreste af disse Segmenter noget opsvuhnet fortil, og det bagerste dan)ier nedentil, ved Basis af Ægbeliolderen, 2 rundagtige Fremspring^ der navnlig er meget tydeligt fremtrædende, naar Dyret sees ovenfra eller nedenfra (se Tab. VI, Fig. 4, Tab. Vni, Fig. li'). De følgende 5 Segmenter er alle af ens Udseende og ogsaa af tilnærmelsesvis samme Størrelse, simpelt cjdindriske, med Længden betydelig større end Breden. Næstsidste Segment er derimod betydelig længere end de ovrige, og sidste omvendt meget kort, neppe mere end halvt saa langt som næstsidste. Det er (se Tab. VI, Fig. 10) tvært afkuttet i Enden og viser i Midten af den bagre Kant en ganske svag Indbugtuing. Til hver Side af denne, og adskilte i Midten ved et større Mellem- rura, er fæstet de smalt lancetformige Halegrene, der maaske, i Liglied med den saakaldte Fnrea hos Copepoderne, kan betragtes som fremkomne ved Klov- ningen af et terminalt Segment, men som dog vel correctest vil kunne beskrives som et Par omformede Lemmer. Hunnens Længde gaar op til 18 mm. Hannen er i Eegelen kj endelig større og opnaar ofte en Længde af indtil 23 mm. Begge Kjøn er desuden let kjendelige ved den meget forskjellige Udvikling af 2det Par Følere, samt ved Beskatfenhedeu af de ydre Kjonsvedhæng. Disse vil passende kunne be- skrives paa dette Sted. maxillæ issue ventrall}' from the cervical seg- ment. The division of the body tliat succeeds the head, the mesosome or truncus, is aboiit same breadth in front as the head, and a little flattened, but narrows a little in its backmost part. It is composed of 11 short and uniformly developed seg- ments, of which each carries a pair of branchial feet. These last follow after each other at regular short intervals, forming with their various lobes and numerous bristles a broad fringe on either side. In this way there is produced along the un- derside of the mesosome a canalular cavity, borde- red by all the branchial feet, which gradually in- creases somewhat in breadth in front, where it joins up to the oral region. The metasome or tail is extraordinarily slen- der, considerably narrower than the mesosome, and of regular cylindrical shape. It occupies appreciably, more than half the entire length of the body, and is composed of 9 segments besides the caudal rami. Of these segments, the 2 foremost ones are only distinct^ separated in the dorsal part, whilst they ventrally pass over into each other, and form here the origin of the outer sexual appendages. These 2 first segments of the tail may, therefore, sui- tably be named «the sexual segments». In the female the foremost of these segments is somewhat swollen in front; and the backmost forms downwards, at the base of the marsupium, 2 roundish pi'ominences, which are, especially, very distinct!}^ prominent when the animal is viewed from above or from below (see PI. VI, fig. 4, PI. VIII, fig. 11). The succeeding 5 segments have all a iiniform appearance, and are also of approximately the same size, plain cylin- drical, with the length considerably greater than the breadth. The penultimate segment is, on the contrary, considerably longer than the others, while, on the other hand, the last is very short, scarcely more than half as long as the penultimate one. It is (see PI. VI, fig. 10) transversally truncated at the extremity, and in the middle of the ])osteripr edge shows a quite faint sinus. On either side of this, and se]iarated in the middle by a lar- gish interval, the narrow lanceolate caudal rami are attached, which, perhaps, like the so-called furca in the Copepods, may be considered as pro- duced by the splitting of a terminal segment, but which, however, probably more correctly may be described as a pair of transformed appendages. The length of the female reaches up to 18 m. m. The male is, as a rule, appreciably larger, and fre- quently attains a length of 23 m. m. Both sexes are, further, easily recognizable by the very different development of the 2nd pair of antennæ, and by the character of the outer sexual appendages. These may lie conveniently described here. 44 Hos Hunnen (Tab. VI, Fig. 3, 4) danner de ydre Kjønsvedliæng en enkelt bagudrettet, poseformig Be- holder af meget smal, næsten cylindrisk Form, dog gradvis noget tiltagende i Tykkelse mod Enden. I sin fulde Udvikling rækker den næsten til Enden af næstsidste Halesegment; men er ofte en Del kor- tere. Sæd vanligvis sees i dens indre et større eller mindre Antal af Æg af mørkegrøn Farve, ordnede i 2 eller flere Rader. Enden af Ægbeholderen er noget koniskt tillobende og bestaar af 2 ved sær- egne Miiskler bevægelige Klapper, der begrændser en tværliggende spaltformig Aabning, bvorigjennem Æggene ndstedes. Den ventrale Klap er noget mere fremragende end den dorsale og ender med et lidet papilleformigt Fremspring (se Tab. VIII. Fig. 11). Hos Hannen (Tab. VI, Fig. 1 og 2) er Kjøns- bængene dobbelte og meget smaa. De ndspringer (se Fig. 11) hvert med en temmelig bred Basis fra Siderne af de 2 Kjønsringe og retter sig skraat nedad og bagnd. Fortil viser de nær sit Udspring en dybt indstikkende Bugt, som begrændses oventil af en sammentrykt triangulær Lap, nedentil af en konisk tilspidset Fortsats. Den ydre Del af Ved- hænget er simpelt cylindriskt, og fra dens stumpt tilrundede Ende sees undertiden en uregelmæssig sagtakket Vorte at skyde frem, egentlig en Udkræng- ning af vas deferens. Legemet er hos begge Kjon i hoi Grad gjennem- sigtigt, saa at de indre Organer, navnlig den med rodgiilt Indhold fyldte Tarmkanal, tydeligt skinner igjennem de tynde Integnmenter. Farven er noget vekslende efter Lokaliteterne, snart meget bleg, hvidagtig, snart med et mere eller mindre tydeligt rødligt eller grønligt Anstrøg. Beslirivelse af Kroppens Yedhitiig. Øinene (Tab. VI, Fig. 9; Tab. VII, Fig. 1 og 2, 0), der rager frem til hver Side fra den forreste Del af Hovedet, er stilhede og viser idethele en meget lignende Bygning som hos JSehalia, skjøndt deres Bevægelighed er langt mere begrændset. Af Form er de næsten kelledannede, idet de gradvis udvides mod Enden, der er noget skjævt tilrundet. Den egentlige Øienglob, der indtager omtrent Vs af Øiets Længde, indeholder en oval eller elliptisk An- samling af mørkt Pigment, omgivet udåd af en klar Zone, hvori de ydre lysbrydende Dele af Syns- elementerne har sin Plads (se Talj. VIII, Fig. 6). Nogen ydre Facettering er ligesaalidt tilstede her som hos Nebalia. — Midt imellem Øinene sees i det Indre af Hovedet en dyb sort Pigmentplet, som er det saakaldte Ocellus eller enkle Øie. In the female (Pl. VI, tigs. 3, 4), the outer sexual appendages form a single, bag-formed reservoir directed backwards, of very narrow, almost cylind- rical shape, but increasing gradually somewhat in thickness towards the extremity. In its full develop- ment it extends almost to the extremity of the pe- nultimate segment, but is often somewhat shorter. There is usually seen in its interior a larger or smaller number of ova of dark green coloiir, arranged in 2 or several series. The extremity of the mar- siipium runs somewhat conically out, and consists of 2 Haps, moveable by means of peculiar mus- cles, which define a transversal fissure-like aper- ture through which the ova are expelled. The ventral flap is somewhat more projected than the dorsal one, and terminates in a small papilliform prominence (see PI. VIII, fig. 11). In the male (PI. VI, figs. 1 and 2), the sexual appendages are double and very small. They issue, (see fig. 11), each with a pretty broad base, frojn the sides of the 2 sexual segments and are di- rected obliquely doAvnwards and backwards. They exhibit in front, near their origin, a deep sinus, which is defined above by a compressed triangular lobe, and below by a conically pointed projec- tion. The outer part of the appendage is plain cylindrical, and from its bluntly rounded extremity an irregularly serrated nipple is sometimes seen to project, really a bulging out of the vas deferens. The body, in both sexes, is in a high degree transparent, so that the internal organs, especially the intestinal canal, filled with red-j'ellow contents, shine distinctly through the thin integuments. The colour is somewhat variable, according to the locality, sometimes very pale, whitish, sometimes with a more or less distinct reddish or greenish tinge. Description of the appeudai^es of the body. The eyes (PI. VI, fig. 9; PI. VII, figs. 1 and 2, 0), which project forwards on either side of the foremost part of the head, are distinctly peduncul- ated, and altogether exhibit a very similar structure to those of Nebalia, although their mobility is far more limited. They are almost claviform in shape, as they become gradually dilated towards the extre- mity, which is somewhat obliquely rounded. Tlie real ocular globe, which occupies about Vs of the eye, contains an oval or elliptical collection of dark pigment, surrounded outwards by a clear zone in which the outer refracting portions of the visual elements have their position (see PI. VIII, fig. (3). Any external facetting is just as little present here as in Nebalia. Midway between the eyes there is seen, in the interior of the head, a deep black pigment-patch, which is the so-called ocellus or simple eye. 45 Første Par Folere (Tab. VI, Fig. 9, a' ; Tab. VII, Fig. 1, 2, a') er meget smaa og simpelt hyggede, dannende hver en meget smal eylindrisk, eller næ- sten traadformig Stamme, paa hvilken ingen tyde- ligt iidpræget Leddeling kan paavises. De er sæd- vanligvis rettede skraat fortil og udåd (se Tab. VI, Fig. 1 — 4), men kan ogsaa til en vis Grad bevæges i andre Retninger, ligesom de idetliele er meget boielige. Paa Spidsen, der er noget skraat afskaa- ret, bærer de (se Tab. VIII, Fig. 2) en Gruppe af 8 j-derst smaa og delikate Sandsevedhæng, som ved stærk Forstørrelse (Fig. 3) viser en stavdannet Form, med et kort, dobbelt contureret Fodstykke og en liden klar Blære ved den stumpt afrundede Spids. Ifølge sin Bygning maa disse Vedbæng nærmest betragtes som Lugtepapiller; medens de o betydelig længere, og i en fin Spids udgaaende Vedbæng, som udspringer i nogen Afstand fra liine fra en afrundet Forhøining, utvivlsomt er at anse som ægte Fole- børster. Andet Par Folere, der udspringer fra Hovedets nedre Flade umiddelbart nedenfor og lidt indenfor det Iste Par, er meget forskjellige hos de 2 Kjøn. Hos Hunnen er de (se Tab. VI, Fig. 9, a^ Tab. VII, Fig. 1, a'^1 forholdsvis smaa og simple, dannende et Par, som det synes fuldkoramen ubevægelige fra Hovedet nedhængende pladeformige Flige. De er omtrent af samme Længde som Oinene og næsten triangulære i Form, idet de udspringer med en tem- melig bred Basis og gradvis afsmalnes mod Enden, som er meget skraat afskaaret, med det bagre Hjorne uddraget i en skarp Spids. I sin forreste Kant har de nogle yderst smaa Foleborster, men er forovrigt ganske ubevæbnede. — Hos Hannen er disse Folere (se Tab. VI, Fig. 1, 2; Tab. VII, Fig. 2, a^) langt stærkere udviklede og omformede til kraftige Gribe- redskaber, hvormed Hunnen fastholdes under Copu- lationen. I Hviletilstand er de mere eller mindre stærkt ombøiede mod Bugsiden og rækker i denne Stilling omtrent til Midten af Forkroppen. Man kan paa dem adskille to skarpt begrændsede Afsnit: et tykt cylindriskt og stærkt muskuløst Skaft, og en tynd kloformig Endedel. Skaftet viser ved Basis flere circulære Indsnoringer, der antyder 3 til 4 ufuldstændigt sondrede Led. Yderdelen af Skaftet har indad en noget tilskjærpet Kant, forsynet med en Række af smaa Tænder, og ved Enden, indenfor Endedelens Insertion, findes en liden konisk tilløbende Knude, eller rettere Bigren. Endedelen er noget kortere end Skaftet og meget smalere, men af sær- deles fast cliitinøs Consistens. Den er bevægeligt articuleret med Skaftet og mere eller mindre stærkt indboiet, samt gradvis afsmalnende mod Spidsen, som er stumpt tilrundet. I Modsætning til hvad Til- fælde er hos Hunnen, er disse Følere hos Hannen The first pair of antennæ (Pl. VI, fig. 9, a'; Pl. VII, figs. 1, 2, a') are very small and simple in structure, each forming a very narrow cylindrical or almost filamentous stem, upon which no distinctly distinguished articulation can be shown. They are usually directed obliquely forwards and outwards (see PI. VI, fig. 1 — 4), but may also, to a certain extent, be moved in other directions, while they are also, upon the whole, very flexible. At the tip, which is somewhat obliquely truncated, they carry (see PI. VIII, fig. 2) a group of 8 extremely small and delicate sensory appendages, which on a power- ful magnification (fig. 3) exhibit a rod-like shape, with a short, double-contoured foot-piece, and a small clear vesicle at the bluntly rounded point. From their structure those appendages must be chiefly considered as olfactory papillæ, whilst the 3 considerably longer, and to a fine point issuing, appendages, which spring from a rounded prominence at some distance from the former, must indubitably be considered as ge- nuine sensory bristles. The scecond pair of antennæ, which issue from the lower surface of the head immediately below and a little inside of the 1st pair, are very difi'erent in the 2 sexes. In the female they are (see PI. VI, fig. 9, a^ PI. VII, fig. 1, a^) relatively small and simple, forming a pair of apparently perfectly im- moveable plate-formed flaps hanging from the head. They are of about same length as the eyes, and almost triangular in shape, as they issue with a pretty broad base and gradiially diminish in breadth towards the extremity, which is very obliquely trun- cated, with the posterior corner drawn out to a sharp point. On the foremost edge they have a few extremely small sensory bristles, but are otherwise perfectly unarmed. In the male these antennæ (see PI. VI, fig. 1, 2, PI. VII, fig. 2, a^) are far stronger developed, and are transformed into powerful prehen- sile organs by which the female is firmly held during copulation. In a condition of repose they are more or less greatly recurved towards the ventral side, and in that position extend to the middle of the anterior body. We are able to distinguish upon them two sharply defined divisions; a thick cylind- rical and strongly musculous shaft, and a thin claw-shaped terminal part. The shaft exhibits se- veral circular constrictions at the base, which indi- cate 3 to 4 imperfectly separated joints. The outer part of the shaft has, inwards, a somewhat sharp- ened edge, furnished with a series of small teeth; and at the extremity, to the inside of the insertion of the terminal part, there is found a small nodule, or more correctly speaking an accessory branch, which runs out conically. The terminal part is somewhat shorter than the shaft and much narrower, but of particularly firm chitinous consistency. It is movably 46 meget bevægelige og kan tilsammen virke som et meget kraftigt tangformigt Griberedskab. Af Munddeleiie er Overlæben og de 2 Kind- bakker let ioiiiefaldende. Derimod er de 2 Par Kj se- ver meget vanskeligere at opdage og lader sig egent- lig kun nøiere nndersoge ved Dissection. Overlæben (Tab. VI, Fig. i), L; Tab. VII, Fig. 1, L; Fig. 3) har Formen af en aflang Lap, der fra Hovedets Ventralside strækker sig bagtil, og sædvan- ligvis fuldstændig dækker overKindbakkernesTygge- dele (se Tab. VI, Fig. 9). Den viser paa Midten en svag Udvidning og ender med en stump Spids, hvis Kanter er fint eilierede. Dens ydre Flade er noget convex, medens den indadvendte Flade er plan eller concav og laadden af fine, tildels gruppevis ordnede Haar. Ved Hjælp af flere stærke Muskler, som fra Hovedet passerer igjennem dens Indre, kan den snart loftes op fra Kindbakkerne, snart præsses ind mod dem igjen. Ind under dens Basis ligger (se Tab. VII, Fig. 3) Mundaabningen i Form af en tvær- oval Spalte, der bagtil begrændses af en ubetydelig fremspringende, haaret Kant. Nogen egentlig Under- læbe er derimod ikke tilstede. Kindbakkerne (Tab. VI, Fig. 9, M; Tab. VII, Fig. 1, M; Fig. 4) er af meget kraftig Bygning og omslutter som et Par Boiler den nedre Del af Ho- vedet paa Grændsen mellem dets forreste og bagerste Parti. Det convexe baadformige Corpirs, der saa- godtsom fuldstændig udfyldes af de kraftige, indad convergerende Tyggemuskler, ender oventil i en Spids, der er bevægeligt indleddet til Hovedets^ Inte- gument ved Enden af den dorsale Sutur, der be- grændser Nakkesegmentet fortil. Den ventrale Ende, eller den egentlige Tyggedel, er (se Tab. VII, Fig. 4) stærkt indboiet og begrændset fra Corpus ved en .svag Indknibning eller Hals. Den er staimpt afkuttet i Enden og har en oval Tyggeflade, der ved stærk Forstørrelse (Fig. 5) viser sig fint riflet paatværs, med den ydre Del af Riflerne noget grovere og besat med Rækker af tæt sammentrængte tandformige Fremspring. Af nogen egentlig skjærende Del, er der imidlertid intetsomhelst Spor. De 2 Par Kjæver kommer først tilsyne, naar man betragter Dyret fra Bugsiden, efterat de for- reste Branchialfødder er fjernede eller lagte om til Siderne (se Tab. VI, Fig. 9, m>— m-; Tab. VII, Fig. 1, m^—m^). De er begge forlioldsvis smaa og af enkel Bygning. — Forste Par (Tab. VII, Fig. (5) bestaar articulated with the shaft and more or less strongly incurved, and gradually diminishes in breadth to- wards the point, which is bluntly rounded. In con- trast to what is the case in the female, these antennæ are, in the male, very mobile, and can act together as a very powerful forceps-formed prehensile ap- paratus. Of the oral parts, the upper lip and the 2 man- dibles are readily visible. On the other hand, the 2 ])airs of maxillæ are miich more difficult to dis- cover and can, in reality, only be closely investigated upon dissection. The anterior lip (PI. VI, fig. 9, L; PI. VII, figs. 1, L; fig. 3) has the shape of an oblong lobe, which extends backwards from the ventral side of the head, and usually completely covers over the masti- catory parts of the mandibles (see PL VI, fig. 9). It exhibits at the middle a faint dilation, and ter- minates in a blunt point whose edges are finely ciliated. Its outer surface is somewhat convex, while the inwards turned surface is plane or con- cave, and flufty with fine hairs arranged partly in groups. With the aid of several strong muscles which from the head pass through its inside, it can easily be raised up from the mandibles, and be easily again pressed in towards them. In below its base lies the oral aperture, in the shape of a trans- verse-oval fissiire, which is bordered behind by an inconsiderably projectant hirsute edge. Any real posterior lip is, on tlie contrary, not present. The mandibles (PI. VI, fig" 9, M; PI. VII, fig. 1, M, fig. 4) are of very powerful structure, and enclose, like a pair of bows, the lower part of the head at the limit between the anterior and posterior portions. Tlie convex cymbiform corpus, which is almost completely occupied by the power- ful, inwards-convergent masticatory muscles, ter- minates above in a point, which is movably arti- culated to the integument of the head, at the ex- tremity of the dorsal suture which limits the cer- vical segment in front. The ventral extremity, or the real masticatory part, is (see PI. VII, fig. 4) strongl}^ incurved and defined from the corpus by a faint constriction or neck. It is bluntly truncated at the extremity, and has an oval masticatory sur- face which upon powerful magnification (fig. 5) shows itself to be finely fluted transversally, with the outer part of the flutings somewhat coarser, and beset with series of closely crowded dentiform pro- jections. Of any real cutting part there is, liow- ever, no trace. The 2 pairs of maxillæ appear first to view when we observe the animal from the ventral side after the foremost branchial feet have been removed or placed away to the sides (see I'l. VI, fig. i) m.' — m.'''; .PI. VII, fig. 1 m.' — m."). They are both rela- tively small and of simple structure. — The first 47 af en tyk miiskulos Basaldel og en med denne be- vægeligt forbnnden og stærkt indboiet Endedel. Denne sidste har Formen af et triangnlært Blad, der paa sin frie, lige afskaarne Rand er besat med en Række af stive Borster, tiltagende i Længde indad. Enhver Borste bestaar (Fig. 7) af en noget tykkere Basaldel besat i den ene Kant med grove Pigge, og en i en fin Spids ndlobende, og i begge Kanter tæt cilieret Endedel. — Andet Par Kjæ- ver (Fig. 8) er langtfra saa kraftigt udviklede og synes heller ikke ifolge sin Stilling at kunne spille nogen væsentlig Rolle ved Næringsoptagelsen. De ndspringer (se Fig. 1, m-) lidt bag Iste Par og er, ganske i Modsætning til hine, rettede udåd. Basal- delen har paa den nedre Side 3 tykke Fjærborster. Endedelen synes kun at være lidet bevægelig og viser en noget oval Form. Dens udadvendte Side er tæt besat med stive, kort cilierede Borster, der staar i flere Rækker og divergerer til alle Sider. Den forreste Borste er noget grovere end de ovrige og fæstet i nogen Afstand fra disse til et kort Fremspring. Branchialfodderne (se Tab. VII, Fig. 9—13) er alle ndpræget bladformige og af temmelig bred Form, med den forreste Flade noget hvælvet og den ba- gerste mere eller mindre concav. Man kan paa dem adskille de samme Hoveddele, .s.om allerede ovenfor er beskrevne paa Branchialfodderne hos NehaJia. Basaldelen eller Stammen er af aflang Form og næten ens Brede overalt. I dens Indre sees for- skjellige hiuanden delvis krj'dsende Muskelbundter, der dels tjener til at boie selve Stammen, dels vir- ker paa de forskjellige Vedhæng. Stammens ydre Kant er noget fortj-kket og viser ved Basis nogle svage Ind- og Udbugtninger som en Antydning til en Slags ufuldstændig Leddeling. Dens indre Kant er delt i 5 korte Lappe, de saakaldte Enditer, hvoraf den bagerste, eller overste, er meget bx-ed og langs sin halvmaaneformigt buede Rand besat med en tæt Rad af kamformigt ordnede og stærkt krummede Børster, alle lint cilierede og be.staaende af 2 tyde- lige Led (se Fig. 10). De ovrige Lajipe er meget mindre, næsten af mammilledanuet Form, og besat med lignende krummede Borster, samt desfoniden foran dem med et Knippe betydelig grovere saa- danne. Endopoditen (end), der danner den umiddel- bare Fortsættelse af Stammen, er forholdsvis ganske kort og har Formen af en bred triangulær, noget indadrettetPlade, besat langs Yderkanten med stærke Fjærborster, der ved Spidsen og langs den indre Kant efterhaanden antager (Jharacteren af korte Torne, cilierede kun i den ene Kant. Exopoditen (ex), der er bevægeligt articuleret til en særegen Afsats af Stammen ved Yder.siden af Endopoditen, pair (Pl. VII, fig. 6) consist of a thick, musculous basal part, and a strongly incurved terminal part connected movably with it. The last-named has the form of a triangular lamella which, upon its free, straightly truncated margin, is beset with a series of stiff bristles, increasing in length inwards. Each bristle (fig. 7) consists of a somevs^hat thicker basal part, beset on the one edge with coarse spikes, and a terminal part which runs out in a fine point and is closely ciliated on both edges. — The second pair of maxillæ (fig. 8) are far from being so power- fully developed, and neither do they, from their position, appear to play any material part in the securing of nourishment. Thej^ issue (see fig. 1 m.^) a little behind the 1st pair, and are, quite in con- trast to them, directed outwards. The basal part has 3 thick plumose bristles on the lower side. The terminal part appears to be only little mobile, and exhibits a somewhat oval form. Its outwardly turned side is closely beset with stiff, short ciliated bristles placed in several series, and divergent to all sides. The foremost bristle is somewhat coarser than the others, and is attached at some distance from them to a short projection. The branchial feet (see PI. VII, figs. 9 — 13) are all prominently foliaceous and of pretty broad form, with the foremost surface somewhat convex, and the backmost one more or less concave. "We can distinguish in them the same chief parts as have already been described above concerning the branchial feet of Nebalia. The basal part or stem is of an oblong shape, and almost uniform in breadth throughout. In its interior may be seen various bundles of muscles pai'tly traversing each other, which serve partly to bend the stem itself, partly act on the various appendages. The outer edge of the stem is somewhat thickened, and at the base ex- hibits a few faint in- and out- curvatures, as an indication of a kind of imperfect articulation. Its inner edge is divided into f) short lobes, the so-called endites, of which the backmost or uppermost one is very broad, and along its semi-lunary arcuate margin is beset vrith a close series of strongly curved bristles arranged like a comb, all finely cili- ated and consisting of 2 distinct joints (see fig. 10). The other lobes are much smaller, almost mammilli- form in shape, and beset with similar curved brist- les, and besides, in front of them, with a fascicle of considerably coarser setæ. The endopodite (end) Avhich forms the immediate continuation of the stem, is, comparatively, quite short, and has the form of a broad triangular, somewhat incurved plate, beset along the outer edge with strong plumose setæ, . wliich at the tip and along the inner edge succes- sively assume the character of short spines, ciliated onlv on the one edge. The exopodite (ex) which is 48 har Formen af et ovalt Blad, rundt om besat med en Rad af Fjærbørster. I nogen Afstand fra Exo- poditen, omtrent ved Midten af Stammens Yder- kant, er Epipoditen (ep) fæstet. Den repræsente- res af et forholdsvis ikke meget stort, simpelt, aflangt, sækdannet Vedhæng. der er rettet skraat nedad og bagud. I sin finere Structur skiller den sig noget fra de øvrige Vedhæng, idet den er af mere spongios Beskaffenhed, og antager paa Spiri- tusexemplarer meget snart et temmelig opakt Ud- seende. Foruden de nævnte Hoveddele, som alle ogsaa er tilstede hos Xehalia, kommer her endnn til et særegent Vedhæng, der er specielt eiendomme- ligt for Gruppen Anosfraca, og som jeg ovenfor har benævnt «Dækpladen», for at antyde dets Bestemmelse, der nærmest synes at være den, til en vis Grad at erstatte det manglende E3'gskjold ved at dække over Eoden af Branchialfodderne. Dette Vedhæng (b) udgaar ligeledes fra Ydersiden af Stammen, men lige ved dennes Rod, og har For- men af en meget tynd og gjennemsigtig oval Plade, regelmæssigt sagtakket i Kanterne. — Undersoger man noiere de 11 Par Branchialfndder og sammen- ligner dem med hverandre, vil man finde enkelte mindre Difterentser i deres Bygning. Hvad for det første Størrelsen angaar, saa tiltager de gradvis noget i Længde fra Iste til omtrent 5te Par, for saa jevnt at aftage i Størrelse bagtil, saa at sidste Par neppe er halvt saa stort som 5te og noget min- dre end Iste. Det forreste Par (Fig. 9) skiller sig fra de følgende ved en noget ringere Udvikling af Exopoditen, medens Endopoditen er forholdsvis stær- kere fremspringende, mindre indadrettet, og kun for- synet med en enkelt Torn i Inderkanten. Sidste Par (Fig. 12) udmærker sig fra de øvrige derved, at Epipoditen har antaget Characteren af en tynd Plade, besat i Kanterne med cilierede Borster, og derved at Dækpladen ganske mangler. Endopoditen er paa dette Par meget kort og af afrundet Form, medens Exopoditen er vel udviklet. — Hos Hannen skiller Branchialfodderne (Fig. 13) sig kjendeligt fra samme hos Hnnnen ved Endopoditens betydelig stær- kere Udvikling. Den er navnlig paa de midterste Par stærkt fremspringende indad, næsten af le- dannet Form, og forsynet med et stort Antal af Randtorner. Rimeligvis har denne Modification af Endopoditen hos Hannen et vist Hen.syn til Copula- tionen, idet Branchialfødderne derved delvis kan fun- gere som et Slags Griberedskaber og derved under- støtte 2det Par Antenner i deres Function at fast- holde Hunnen under Parringen. movably articnlated to a separate ledge of the stem at the outer side of the endopodite, has the form of an oval lamella, beset all round with a row of plu- mose setæ. At some distance from the exopodite, aboiit in the middle of the outer edge of the stem, the epipodite (ep) is secured. It is represented by a, comparatively, not very large, simple, oblong vesicu- lar appendage, which turns obliquely downwards and backwards. In its microscopical structure it differs somewhat from the other appendages, exhibiting a more spongious character, and in alcoholic specimens it very soon assumes a rather opaque appearance. Besides the above named chief parts, which are all also present in Nehalia, another peciiliar appendage is here added, which particularly distinguishes the group Anostmca, and which I liave named above «the covering plate», in order to indicate its most probable purpose, viz , to replace to a certain extent the absent carapace in covering over the base of the branchial feet. This appendage (b) issues likewise from the outer side of the stem, but close to the base of the latter, and has the form of a very thin and pellucid plate, regularly serrated on the edges. — On a closer examination and comparison of the 11 pairs of branchial feet, some minor differences in their structure will be found to exist. Firstly, as regards the size, they increase successively somewhat in length from the 1st to about the 5th pair, after which thej^ again gradually decrease in size, in such a manner that the last pair are scarcely half as large as the 5th and also somewhat smaller than the 1st. The foremost pair (fig. 9) differ from the succeeding ones by a somewhat slighter development of the exopodite, whereas the endopodite is com- paratively more strongly produced, less incurvate, and only provided Avith a single spine on the inner edge. The last pair (fig. 12) distinguish themselves from the others by the epipodite having assumed the character of a thin plate edged with ciliated bristles, and by the complete want of any covering plate. The endopodite is, on this pair, very short and of rounded shape, whereas the exopodite is well developed. In the male the branchial feet (fig. 13) distinguish themselves very markedly from the same in the female, by the much stronger development of the endopodite. The latter is, especially on the middle pairs, strongly produced inwards, almost falciform in shape, and jjrovided with a great num- ber of marginal spines. In all probability this mo- dification of the endopodite in the male has a cer- tain relation to the act of copulation, since the lirancliial feet thereby become, to a certain extent, enabled to act as a kind of prehensile organs, thus assisting the 2nd pair of antennæ in their function to retain hold of the female dui-ing copulation. 49 Indre ()ri,'tiiu'r. Internal Organs. J)eii imlrc ( )rganisatii:in er licis nærværende Poriii ikke saa særdeles vanskelii;- at studere, da Dyrets store (TJeniiemsigtiglied gjor det muligt at cibservere saagodtsom alle indre (.)rganer i sin Sitns, uden at nogen Dissection er foruoden. Paa de her givne Habitusfigurer i Tab. VI. Fig. 1— 4i er de vig- tigste indre Organer antydede, saaledes som de viser sig ved en svag Forstorrelse. Paa Tab. VII er af- bildet Detailler af Nervesystemet, Fordoielsessyste- niet og Kjonssystemet i stærkere Forstorrelse. Fordøielsessystemet. — Tarmtraetus liestaar af ij tydeligt begrændsede Dele, nemlig S])iseror, Chy- lustarm og Endetarm. Spiseroret er meget kort, stærkt nuisknlost, og stiger lodvet oji fra Mnnd- aabningen til den forreste, i Hovedet beliggende Del af Tarmen. Denne .sidste Del er noget ndvidet og viser, overensstemmende med Legemets Konturer, en svag Krumning, men gaar forovrigt umærkeligt over i den bagenfor liggende Del af Tarmen, uden at A'ære begrændset fra samme som nogen virkelig Mave. Fortil udsender denne Del til hver Side en afrundet blindsækfurmig Udvidning, som bedst sees, naar Legemet betragtes ovenfra (Tab. VI, Fig. 4). A'ed nærmere Undersogelser viser enhver af disse Udvidninger sig stærkt foldet ise Tab. VIII, Fig. 10\ eller ligesom bestaaende af et Antal uregelmæssige secundære Udposninger, alle indvendigt beklædte med et kjertelagtigt Epithel, der delvis ogsaa fort- sætter sig ind i selve Tarmen. Der er ingen Tvivl om, at disse 2 blindsækformige LTdvidninger af Tar- men er homologe med det hos andre Phyllopoder i Hovedet lieliggende complicerede kjertelagtige Organ, man ialmindelighed har kaldt Leveren, men som hos nærværende Gruppe er stærkt reduceret og saa- ledes paa en Jlaade danner Overgangen til de simple blindsækformige Appjendiees, der foretindes paa samme Plads hos visse Cladoccrer. Ligeledes maa de oven- for beskrevne saakaldte Leversække hos NvhaJia an- tages at hore ind under samme Kategori, skjondt kun et Par af disse strækker sig ind i selve Hove- det. Tarmen danner forovrigt (se Tab. VI, Fig. 1 — 4) et simpelt eylindriskt, med stærke Ringmuskler for.synet Ror, der irden nogen Bugtninger strækker sig gjennem Dyrets Axe indtil Halens sidste Seg- ment, hvor den forbinder sig med Endetarmen. Denne sidste (se Fig. 10), der altsaa kun er ind- skrænket til sidste Halesegment, er, som det ovrige Tarmror, forsynet med stærke Ringmuskler og des- uden ved straaleformigt til dens Overtiade gaaende Muskelfibre fixeret i sin Stilling. A^ed Hjædp af alle disse Muskler bliver denne Del af Tarmtraetirs meget bevægelig og kan vexelvis stærkt indsnores og udvides. hvad der liar sin Betydning ved Ud- tommelsen af Ex(/rementerne. Medens I)yret lever, observeres paa Tarniroret meget energiske peristal- ~ — ^i. O. S:irs: Fiuiiia Xasis af Overheben. be observed, these being transmitted with great regularity throughout its entire length, generally from behind forwards. Circulatory system. — The heart (see PL VI, tigs. 2, 3, lie) consi.sts of an exceedingly elongated tube, constricted at I'egular intervals, and extending above the intestine from the cervical segment back- wards into the penultimate segment of the tail. It is attached by fine muscle-fibres to the inside of the dorsal integument, and exhibits, in each segment, a pair of venous ostia, thi-ough which the blood is received into the heart. The accumulated mass of blood, which thus forces itself into the heart, is ex])elled partly trom the anterior, partly from the posterior end, and then enters the several cavities between the various organs. Although there is thus a total absence of a true vascular system (H)nsisting of arteries and veins, yet the blood circulates with great regularity through the body, following certain fixed courses. The blood is, as usual, colourless, and contains a number of small, partly am(jel)ous blood-corpuscles, whose course may be easilj' traced under the microscope. The pulsations of the heart, during which the o.stia alternately open and close, are exceedingly rajnd, so that it is very difficult to count the iiumlier occurring in a minute. Nervous system. — The central portion of the nervous system consists, as in other (.'rustaceans, of a dorsal part, the supraæsophageal or cerebral ganglion, and of a ventral part, the so called ventral ganglion chain, connected with one another by a commissure round the æsophagus (see PI. VIII, fig. 1). The cerebral ganglion (see figs. 1, 4 and 17), which is situated in the anterior part of the head, just in front of the commencement of the intestine, is of considerable size, and consists of 2 symmetri- cal halves connected with one another in the middle. Above, it forms several lobes which partially sur- round the base of the ocellus (see fig. 4), and, after sending out a fine nerve to each of the first pair of antennæ (a'), continues on each side in the form of the ])Owerfully developed optic nerve (oV A second pair i>f nerves are seen to issue from the cerebral ganglion farther forward, on each side of the ocellus. They each end in a little ganglionic protuberance immediatel\- below a small pit-like depression in the anterior integument of the head ^a) ]irobal)ly an- swering to the ciliated pits occurring in ahout the same place in Liimifitix, and whicli are generally considered to l)e a kind of organ of sense, 'ilii' nerves for the second [lair of antennæ (a ''^) whicli are considerably stronger in the males than in the females, originate from tlie anterior part of the (esophageal commissures. These, before they encircle the æsojdiagus, are connected by a thin transverse commissure (see figs. 1 and 4) lying near the base of the anterior lip. 51 -Buggangliekjæden (se Fig. 1) er ikke vanskelig at observere saavel hos levende Exemplarer som hos Specimina opbevarede i fortyndet Spiritus. Man behover bbit med Forsigtighed at udbrede Branchial- fodderne til hver Side og ind.stille Mikroskopet skarpt paa Bngtladen af Dyret, og denne Del af Nerve- sjj-stemet vil, ialfald delvis, klart og tydeligt sees, nden at nogen virkelig Dissection er fornøden. Dog er dens forre.ste Del altid temmelig vanskelig at ob- servere, da den fordetmeste skjnles af de lidet gjen- nemsigtige Kindbakker og af Kjæverne. Buggang- liekjæden viser en meget udpræget stigedannet Form, idet den bestaar af 2 vidt adskilte stærke Nerve- stammer, som i hvert Segment forbindes med en dolibelt Tværcommis.snr. Paa dette Sted viser hver Nervestannne en temmelig svag ganglios Opsvulm- ning (se Fig. 5), fra hvis ydre Side 2 .stærke Xerver ndspringer. Det ene Par af disse Nerver trænger ind i de respective Branehialfodder, medens det andet Par synes at innervere de Muskler, der fra Kroppen pas.serer til Basis af disse Lemmer. En anden betj'delig svagere Nerve ndspringer omtrent fra Midten af enhver af Længdeeommissurerne og synes at ende i Legemets Sidemnskler. Antallet af de Nerveknnder, der sammen med Commissurerne danner Buggangliekjæden, er paa hver Side 15 (se Fig. 1). Heraf er de 3 foi'reste Par bestemte for Kindbakkerne og de 2 Par Kjæver, det bågeste Par for Genitalsegmentet. de 11 ovrige for de 11 Par Branehialfodder. Buggangliekjæden er saaledes ind- skrænket til Forkroppen alene. I Bagkro])])en fort- sættes rigtigniik de 2 Nervestammer lige til Enden af sidste Segment, men nden lier at være forbundne ved Tværcomraissurer og uden at danne tydelige (xanglier. I hvert Halesegment udsender disse Nerve- stammer tine Nervegrene, hvoi-af nogle synes at ud- brede sig i Halens Muskulatur, medens andre ender med en liden ganglios Opsvulmning lige under Hixdeu (se Fig. 8). Paa disse Steder sees altid en over- ordentlig fin Borste (Foleborste) at springe frem, til- dels omgiven af snma Hudpapiller (Fig. 9). Angaaende den Maade, hvorpaa de ovrige Ner- ver ender, skal her blot omtales Forholdet med de til Iste Par Folere gaaende Nerver og Synsnerverne. Første Par Foleres Ner\-er ndspringer ise Fig. 4) tilsyneladende fra det basale Parti af Synsnerverne, idet begge Nerver ved sit Udspring er omgivet af en fælles Nerveskede. De træder deretter til hver Side som en tynd Stamme iii