68 



bulacralplader, idet de ere omtrent dobbelt saa store og, 

 istedetfor som de sidste at være transversale eller lang- 

 strakt — rectangulære, have de antaget en noget nær 

 triangulær Form. Begge Plader ligge ganske tæt til hin- 

 anden og ere bevægeligt forbundne med deres imod hin- 

 anden vendte Eand, som er lige og fint tandet. Midt paa 

 deres frie eller nedre Flade sidder paa hver af dem en 

 af Liitken først hos P. militaris og senere af mig hos P. 

 pulvillus bemærket Pig (n), som her neppe er saa stor 

 som de største i Viften staaende (hos P. pulvillus er den 

 oftest større end disse). 



Endelig bemærkes, at hver anden af Adambulacral- 

 pladerne (Fig. 15, f), den nemlig, som bærer en længere 

 Tværfinne, rager lidt længere frem i Bugfuren end hver 

 anden (e), som bærer en kortere Tværfinne. 



Bræmmen langs Skivens og Armenes Rand (Fig. 2, i) 

 er her tykkere, mere kjødagtig end hos de 2 andre Arter, 

 saa at de i den indsluttede store Bandpigge, hvilke ligele- 

 des i Antal svare til Tværfinnerne, først komme tilsyne 

 ved Indtørring. Disse Kandpigge (Fig. 11, 13, Fig. 14, 

 15, h) ere insererede næsten i lige Linie med Tværfin- 

 nerne og i kort Afstand fra disses yderste Pig, paa en 

 noget fremragende Del af Adambulacralpladens ydre Kand, 

 og ere ligesom hos hine 2 Arter tykkere og længere end 

 Tværfinnernes Pigge (midt paa Armene næsten dobbelt 

 saa lange). — Tæt foran og indenfor hver Randpigs Basis, 

 eller nær ved den Adambulacralpladerne adskillende Tvær- 

 fure, altsaa afvexlende med Tværfinnerne, ligger, ligele- 

 des indsluttet i Huden, den af mig hos de 2 andre Arter 

 beskrevne lille Bandpig (Fig. 15, i), der har den samme 

 lidt bøiede lancetdannede Form som hos vore 2 andre 

 norske Arter (se Fig. 18, 21, i). 



Ogsaa Eygsiden af vor Søstjerne frembyder ved nær- 

 mere Undersøgelse nogle Afvigelser fra P. pulvillus. Hul- 

 rummet mellem legge Byggens Huder, hvilket, som vi vide 

 fra P. militaris, er en Klækkehule eller Marsupium og 

 tillige en Respirationshule, der lignende et af Pillarer 

 støttet Felt indtager den hele Rygside, er nemlig her be- 

 tydeligt større end hos de 2 andre Arter og, naar man 

 gjennemskjærer en Straale tværsover Midten af dens 

 Længde, viser det sig at være næsten ligesaa høit som 

 Kroppens eller Indvoldehulen (se Fig. 2). Som Følge heraf 

 ere de i Ryggens netformige (af den indre Ryghud beklædte) 

 Kalkskelet indplantede Paxiller eller PigJcoste (Fig. 3, d, 

 Fig. 5) forholdsvis større. Dette gjælder især om deres Skaft, 

 som paa Skiveryggen (imod Armenes Ende blive Paxillerne 

 som bekjendt overalt efterhaanden mindre) er indtil 4 Mm. 

 høit (hos et ikke betydeligt mindre Exemplar af P. pulvillus 

 knapt 2 Mm.) og 2 / 3 Mm. tykt; dets Top er i Omkred- 

 sen kronet med en Krands af 8—11 tynde Naale og i 

 Centrum af 1 {undertiden 2) længere og betydeligt (2—4 

 Gange) tyMere JSfaal (f), som rager langt ud over hine og 

 foraarsager ved med sin Ende at støde op imod Under- 

 fladen af den ydre Ryghud en liden conisk Vorte eller 



than the other adambulacral plates, being about twice 

 as large; and instead of being like the others transver- 

 sally or longitudinally oblong-rectangular, they have as- 

 sumed a nearly triangular form. Both plates lie quite 

 close to each other, and are movably connected by their 

 contiguous margins, which are straight and finely dentated, 

 In the middle of their free or lower surface, there is on 

 each of them a spine (n) which was first remarked by 

 Lutken in P, militaris, and afterwards by me in P. pul- 

 villus. This spine is here scarcely so large as the largest 

 in the fan (in P. pulvillus it is most frequently larger),, 



Finally we remark that every alternate one of the 

 adambulacral plates (fig. 15, f), namely that one which 

 bears a longer transverse fin, projects a little further in 

 the ventral furrow than every other (e) which bears a 

 shorter transverse fin. 



The Bim along the margin of the disc and of the arms 

 (fig. 2, i) is here thicker and more fleshy than in the 2 other 

 species; so that the large marginal spines enclosed within 

 it, which likewise correspond in number to the transverse 

 fins, only become visible when the animal is dried. These 

 marginal spines (fig. 11, 13. fig. 14, 15, h) are inserted nearly 

 in a straight line with the transverse fins, and at a short 

 distance from the outer spine of the latter, on a somewhat 

 prominent part of the outer margin of the adambulacral 

 plate; and are, as in the previously mentioned 2 species, 

 thicker and longer than the spines of the transverse fins 

 (in the middle of the arms nearly twice as long) Close 

 in front and within the base of each marginal spine, or 

 near to the transverse furrow separating the adambula- 

 cral plates, that is alternating with the transverse fins, 

 lies, also enclosed in the skin, the small marginal spine 

 (ß.g. 15, i) described by me in the 2 other species, and 

 which has the same slightly curved lancet-like shape as 

 in our 2 other Norwegian species (see fig. 18, 21, i). 



Also the dorsal side of our star-fish exhibits, when 

 more closely examined, some differences from the P. pul- 

 villus. The cavity between both the cuticles of the back,, 

 which, as we know from P. militaris, is a hatching-cavity 

 or marsupium, and at the same time a breathing cavity 

 which, like a tent supported by pillars, occupies the whole 

 dorsal side, is here considerably larger than in the 2 other 

 species, and on cutting a ray across in the middle of its 

 length the cavity will appear to be nearly as high as the 

 inner or intestinal cavity of the body (see fig. 2). As a 

 consequence of this the paxillæ or compound spines (fig. 

 3, d, üg. 5) implanted in the reticular calcareous skeleton 

 of the back (and covered by the interior dorsal skin) are 

 proportionally larger. This applies especially to their 

 shaft, which on the back of the disc (towards the end 

 of the arms the paxillæ, as is well Jcnown, become gradu- 

 ally smaller) reaches the height of 4 Mm. (in a not much 

 smaller specimen of P. pulvillus scarcely 2 Mm.) with a 

 thickness of % Mm.; its top is encircled with a crown 

 of 8—11 thin needles (fig. 5, d), with in the centre 1 

 (sometimes 2) longer and much (2—4 times) thicker needle 

 {f) which projects far beyond the others, and produces 



