145 



at' 12 yderst smaa Polder eller Papiller, Tab. XVII. Fig. 

 4 b. Naar Aabningen udvider sig. er den altid stjerne- 

 formig, og ofte adstødes tier da Grus eller Excrenienter, 



hvorefter den lukker sig meget stærkt, san at der kun 

 vises en stjerneformet Pordybning. 



MundskiveD er konisk fremspringende. Tab. V, Fig. 2, 

 forsynet med 12 temmelig brede Folder, der koncentrere 

 sig imod Munden, Tab. XVII. Fig. 3, som er næsteD rund 

 og har jævne men tykke Læber uden Gonidier. Skivens 

 Rand er rund. og paa den sidder i en Ka-kke 1 2 Tentakler, 

 der indtage en Længde af omtrent Trediedelen af Krop- 

 pens, Tab. V. Fig. 2; Tab. XVII. Fig. 3. De ere 

 retraktile. cylindriske, temmelig slanke og ende næsten 

 traadformigt. Ikke alene Tentaklerne men ogsaa Mund- 

 skiven kan indtrækkes og skjules ganske af Kroppens 

 øverste Rand. 



Naar Dyret ved Sammentrykninger forkorter sig, 

 bliver Huden stærkt foldet baadé paalangs og paatvers 

 og faar et rudet Udseende ; i Ruderne træde da Suge- 

 vorterne skarpt frem. Forresten bestaar I!eva'iielserne i 

 Forlængelser og Forkortninger, i Udvidning og Sammen- 

 trækning af Kroppen: men den bagerste Ende trækkes 

 aldrig ind i Legemet. Dyret lever i Sand paa stenet 

 Grund. og efter hvad jeg iagttog ved at have det levende 

 i nogen Tid i Observationskarret, væltede det sig ovenpaa 

 Sandet uden at grave si^i ned i dette. Kun af og til 

 hævede det sin forreste Del af Kroppen og udstrakte Ten- 

 taklerne livligt, imedens Mundskiven skjod sig stærkt frem; 

 men i Almindelighed laa det udstrakt paa Sandets Over- 

 flade og væltede sig til Siderne. 



Farven. Den forreste Del af Legemet er næsten 

 vandklar. spillende lidt i det Rode; den midterste Del er 

 kjødrød med lysere Længdestriber, og den bagerste Del 

 har. naar den ei- udvidet, omtrent samme Farve som den 

 forreste; naar den derimod er sammentrukken, ei' den ogsaa 

 kjødrød. Mundskiven er næsten vandklar. med bleg-rosen- 

 røde i det Violette spillende Straaler (Folder). Tentak- 

 lerne ere lyserøde, næsten vandklare, have ved Granden 

 en brun-violet Flæk, der som en Stribe forhenger sig langs 

 den adorale Side lige til Spidsen, Tab. V, Fig. 2. 



Legemets Overflade er overalt beklædt med et bredt 

 Ectoderm, der bestaar af lange, cilierende Cylinderceller 

 med Kjerne og Kjernelegeme i en finkornet Protoplasma- 

 masse. Tab. XVII, Fig. 6 a ; Tab. XVIII, Fig. 1 a. Imellem 

 Cellerne sees hist og her flaskeformede, encellede Slim- 

 kjertler, hvoraf mange ere fyldte med en finkornet, seig 

 Masse, der skjuler ganske Kjernen, imedens andre ere 

 ganske tomme. Den lidt forlængede Hals munder ud paa 

 Overfladen, Tab. XVIII, Fig. 1 b. Men foruden Slim- 

 kjertlerne er der indleiret imellem Ectodermets Cylinder- 

 celler en stor Mængde Nematocyster. Tab. XVIII, Fig. 1 c, 

 som dog ere i rigest Mængde tilstede paa Mundskiven 



Den norske Nordhavsexpedition. D. C. Danielssen: Actinida. 



suiTounded by 12 extremely small folds or papillæ (Pl. 

 XVII, fig. 4 V). When the aperture dilates itself it is 

 always stelliform, and there is. when in that state, frequently 

 ejected sand or éxcrementa, after which it is verv firmly 

 closed so that there. then. is only a stelliform depression 

 visible. 



The oral disc is conically protuberant (Pl. V, fig. 2) 

 and furnished with 12 rather broad folds that collect 

 round the oral aperture (Pl. XVII, fig. 3), which is 

 rather round. with sinooth but thick lips and no gonidia. 

 The margin of the disc is round. and upon it there is 

 seated a cycle of 12 tentacles. occupying a space equal to 

 a bont one third of the length of the body (Pl. V. fig. 2; 

 Pl. XVII, fig. 3). The tentacles are retractile, cylindrical, 

 and tolerablv slender. and terminate almost filamentously. 

 Not only the tentacles but also the oral disc may be 

 retracted and quite concealed by the superior margin of 

 the body. 



When the animal, liv its contraetion. shortens itself, 

 the integument becomes strongly folded. both longitudinally 

 and transversally. and acquires a chequered appearance, 

 and the suckers then come prominently out in the checks. 

 The movements of the animal, otherwise, consist of pro- 

 longations and shortenings, expansions and eontractions of 

 the body, but the posterior exticmity is never retracted 

 in to the body. The animal lives in the sand of stony 

 bottom, and, from what I observed whilst I had it alive 

 sorae time in the glass vessel. it rolled about on the sur- 

 face of the sand and did not burrow into it. Only now 

 and then did it raise the anterior part ot the body and 

 extend the tentacles vigorously, whilst the oral disc pro- 

 jeeted itself prominently forward; hut in general it lav 

 extended on the surface of the sand and rolled itself to 

 the sides. 



TJie colour. The anterior part of the body is almost 

 pellueid. with a reddish play of colour; the medial part 

 is flesh-coloured with lighter coloured longitudinal stripes, 

 and the posterior part has. when it is expanded. about the 

 same colour as the anterior part; but when, on the other 

 hand, it is contracted it. also. is flesh-coloured. The oral 

 disc is almost pellueid, with pale rosy-red rays (folds) 

 having a violet play of colour. The tentacles are light red. 

 almost pellueid. and at their base have a brown-violet 

 patch which. like a stripe, extends itself along the adoral 

 side right up to the point (Pl. V. fig. 2). 



The external surface of the body is everywhere clad 

 with a broad ectoderm, consisting of long, eiliating cylinder- 

 cells with nucleus and nucleolus surrounded by a finely 

 granulated protoplasmic mass (Pl. XVII, fig. (1 a; Pl. XVIII, 

 fig. 1 a). Between the cells there are here and there 

 seen bottle-shaped, unicellular mucous glands, niany of which 

 are filled with a finely granulated viscid mass that quite 

 conceals the nucleus, whilst others are quite empty. The 

 slightly elongated throat opens on to the external surface 

 (Pl. XVIII, fig. 1 b). But besides the mucous glands there 

 lie entrenched, between the cylinder-cells of the ectoderm. 

 a great ahundance of nematocysts (Pl. XVIII, fig. 1 c), 



19 



