131 



Polyperne ere med Tentaklerne 10—12""" lange, retrak- 

 tile, cylindriske, glatte og aldeles gjennemsigtige, saa at 

 Svælget, G-astralfilamenterne, Septa og G-enerationsorganerne 

 kunne sees; de ere temmelig udvidede, der hvor Bagkrop- 

 pen gaar over i Cellen; men smalner af opimod Tentakel- 

 skiven, Tab. XIX, Fig. 47. Polypkroppen er forsynet 

 med 8, vel adskilte Længderibber, der fortsættes over paa 

 Cellen og ere dannede af Kalkspikler ; imellem disse Ribber 

 er en temmelig bred Fure, som er uden Kalk, Fig. 47. 

 Opimod Tentakelskiven vige Ribberne længere fra hverandre, 

 hvorved dannes trekantede Felter, der ere bredest mod 

 Mundskiven, men har en spids Vinkel nedad; fra denne 

 udgaar en Pyramide af Spilder, der indtager Feltets Midt- 

 parti, imedens den øvrige Del er nøgen, men besat med 

 Nematocyster, Fig. 47, a. Tentaklerne ere 5 — 6 mm lange, 

 meget brede ved Grrunden, men tilspidse sig traadformigt, 

 have paa deres aborale Side en Kjøl af Spilder, Fort- 

 sættelse af Kroppens Bibber, og ere forsynede med tæt- 

 staaende, temmeligt tynde Pinnuler, som ere spikelholdige. 

 Fig. 47. 48. Mundskiven, der i Forhold til Kroppens 

 bagre Del er smal, kun lidet hvælvet, har en tverspaltet 

 Mundaabning og er overalt besat med Nematocyster, 

 hvilket ogsaa er Tilfældet med Tentaklernes adorale Side. 



Ved Grrunden af enkelte Polyper, just der, hvor to 

 saadanne støde sammen, sees yderst smaa Polyper, som 

 ere dannede ved Udbugtning (Knopskydning) af Polyp- 

 væggen og staar saaledes i Forbindelse med Mavehulheden, 

 Fig. 46, c; ligesaa iagttages ved Stammens Grrund flere 

 temmelig smaa Polyper med deres Celler, der synes at 

 være skudte op af Basaldelen, Fig. 46. Naar Polypen. 

 trækker sig ind i sin Celle, krænger den øverste Del af 

 denne sig ind, og da faar Randen et ottetandet Udseende, 

 som Følge af de 8 Spikelrækker, der findes i Cellens 

 Væg, — og naar Polypen er fuldkommen indtrukken, er 

 Cellen nogef forkortet, lidt rynket og frembyder da paa 

 sin øverste, afrundede Ende en ottestraalet Stjerne, i hvis 

 Midte sees en yderst fin, rund Aabning, Fig. 46. En 

 enkelt Polyp kan ikke trække sig fuldkommen ind i sin 

 Celle, uden at dennes Nabocelle forkortes lidt; men have 

 samtlige Polyper trukket sig sammen, er hele Stammen 

 forkortet paa G-rund af Cellernes intime Sammenvoxning, 

 hvorom vi senere skulle faa Besked. 



be considered as the posterior body of the polyp, as in it 

 the gastral cavity becomes prolonged right down to the 

 base. The number of the cells is principally dependent 

 on the size of the colony. In the largest specimens there 

 are nearly 40 of them. 



The polyps, with their tentacles, measure 10 — 12 mm 

 in length; they are contractile, cylindrical, smooth, and 

 perfectly transparent, so that the gullet, gastral filaments, 

 septa and generative organs, may be observed; at the point 

 where the posterior body passes over into the cell, they 

 are pretty much dilated, but diminish in thickness, again, 

 up towards the tentacular disk (PL XIX, fig. 47). The 

 polyp-body is furnished with 8, well-separated, longitudinal 

 ribs which are continued over upon the cell, and are formed 

 of calcareous spicules; between these ribs there is a pretty 

 broad groove devoid of calcium (PI. XIX, fig. 47). In 

 the proximity of the tentacular disk, the ribs diverge con- 

 siderably from each other, causing triangular areas to be 

 formed, which are broadest towards the oral disk and have 

 an acute angle downwards; from that, a pyramid of spi- 

 cules issues, which occupies the mesial part of the area, 

 whilst the remaining part is bare, but beset with nemato- 

 cysts (PL XIX, fig. 47, a). The tentacles measure 5 — 6""" 

 in length, and are very broad at the base but become 

 filamentously acuminated; on their aboral side they have 

 a carina of spicules which are a continuation of the ribs 

 of the body, and they are furnished with closely-placed, 

 rather thin, pinnules containing spicules (PL XIX, fig. 47. 48). 

 The oral disk, which, in proportion to the posterior part 

 of the polyp, is narrow, is only slightly arcuate, and it 

 has a transversally-fissured oral aperture ; it is everywhere 

 beset with nematocysts, which is, also, the case with the 

 acloral side of the tentacles. 



At the base of some polyps, just at the point where 

 two of them join each other, extremely minute polyps are 

 seen, formed by budding of the polyp wall and therefore 

 in connection with the gastral cavity (PL XIX, fig. 46, c). 

 There is observed, also, at the base of the stem, several 

 rather small polyps with their cells, which appear to have 

 sprouted up from the basal part (PL XIX, fig. 46). When 

 the polyp retracts into its cell, the uppermost part of the 

 cell curves inwards, and the margin then acquires an octo- 

 dentate appearance, owing to the 8 spicular series which 

 are found in the wall of the cell; and when the polyp is 

 completely retracted, the cell is somewhat shortened and 

 becomes a little wrinkled, and then it presents an eight- 

 rayed star upon its uppermost rounded extremity, in whose 

 middle an extremely minute circular aperture (PL XIX, 

 fig. 46) is observed. A single polyp can not retract itself, 

 completely, into its cell without the neighbouring cell, also, 

 becoming a little shortened, but if all the polyps have 

 contracted themselves together, the entire stem then be- 

 comes shortened, owing to the intimate concretion of the 

 cells, and of this we will subsequently speak. 



