99 



Gersemiopsis arctica, n. g. et n. sp. 



Tab. XIV. Tab. KV, Fig. 1—13. 



Zoanthodemet er indtil 40""» høit. Stammen er grenet ; 

 ruiid, temmelig haard, riflet etter Længden og omtrent 20""" 

 i Omkreds ved Grunden, men smalner successivt ai imod 

 Toppen, hvor den neppe er 5""" i Omfang, og hvor den 

 ender med en større dirr mindre Gruppe Polyper, Fig, 1, 

 Paa et Exemplar er Stammen rig paa Grene lige fra 

 Grunden og op til Toppen, Fig. 1 : paa tu andre er den 

 nederste Del al Stammen nøgen, saa at Grenene forst be- 

 gynde omtrent 15'"™ ovenfor Besaldelon, Fig. 2. Denne er 

 last. membranagtigt udvidet og omfatter dels døde Koral- 

 stumper, dels Grus eller Smaastene. Grenene staa rundt 

 Stammen, temmelig langt fra hverandre og ere af forskjellig 

 Længde og Tykkelse; de længste ere fra 12 — 15""" lange 

 og omtrent 2""" brede ved Grunden, de ere runde, svagt 

 riflede og bære paa |Enden en Gruppe Polyper; de ndsende 

 flere Smaagrene, der ere korte, tynde og ende hver i 3 : — 6 

 Polyper, hvoraf dels 2, dels 3 ere sammenvoxede ved 

 Grunden,] Fig. 3, imedens ved Siden at disse hyppigt sees 

 en enkelt, isoleret Polyp, Fig. 3, a. Hos det ene Exemplar 

 iagttages paa de fleste Grene, næsten lige ved deres Ud- 

 spring, dels en enkelt Polyp, dels tu, der forene sig ved 

 Grunden. fur at gaa over i Grenen, ligesom der fra selve 

 Stammen udspringe dels enkelte, dels 2 eller 3 samlede 

 Polyper, Fig 1. Paa de to Exemplarer, hvor den nederste 

 Del ai' Stammen er nøgen, udspringe ingen Polyper direkte 

 fra dem 1 . Baade Stammen og Grenene ere rige paa Spikler. 



Polyperne ere cylindriske, men udvide sig noget mod 

 Tentakelskiven, Fig 4; de ere ikke retraktile, 8— 9""" lange 

 med en udpræget Bagkrop, der er 4""" lang; Forkroppen er 

 2,5""" lang og Tentaklerne omtrent 3"'" lange. Paa Kroppen, 

 der er temmelig rig paa Spikler, ordne disse sig i 

 Længderækker, sum fortsættes over paa Tentaklernes aborale 

 Flade, hvor de danne en tyk Kjøl, Fig. 4, imedens Side- 

 raudene, ligesom Pinnulerne, ere uden Spikler, men derimod 

 besatte med Nematocyster, der ogsaa findes paa den nuget 

 hvælvede Mandskive. Munden er aflang me 1 tykke Læber. 



1 Der tindes næsten hos hver Art denne Slags Variationer og 

 ofte endnu storre. som i de fleste Tilfælde gjør det vanskeligt, for 

 ikke at sige umuligt, alene efter Zoanthodemets Ydre at kunne be- 

 stemme Arten. 



Gersemiopsis arctica, n. g. et n. sp. 



Pl. XIV. Pi. XV. figs. 1 — 1 :i. 



The Zoanthodera measures up to 40'"'" in height. 

 The stem is ramous, cylindrical, pretty hard. grooved longi- 

 tudinally, and measures about 20""" in circumference at 

 the base, bul diminishes, gradually, in thiekness towards 

 the summit, at which point it measures, barely, 5""" in cir- 

 cumference, and terminates in a larger or smaller group of 

 polyps (Pl. XIV, fig. 1). ln one specimen the stem is rich 

 in branches, quite from the base and up to its summit 

 (Pl. XIV, fig. 1). In two other specimens the inferior part 

 of the stem is bare, and the branches appear, first, about 

 15""" above the basal part (Pl. XIV, fig. 2). This part is 

 hard and membranaeeously dilated, and it includes, partly, 

 moribund coral lumps, partly, coarse sand ur gravid. The 

 branches are placed around the stem, pretty far apart from 

 each other. and are of variable length and thiekness; the 

 longest ones measure trom 12 — 15""" in length, and about 

 2'"" in thiekness at the base. They are cylindrical, faintlv 

 grooved, and earry on the extremity a group of polyps. 

 They send out several branchlets, which are short, and slender ; 

 each of these, again, terminates in 3— <j polyps, of which. 

 sometimes 2, and sometimes 3, are concreted together at 

 the base (Pl. XIV, fig. 3); whilst, at the side oi' these, there 

 is frequently seen a single isolated polyp (Pl. XIV, 

 fig. 3, a). In the one specimen there is ob3erved, upon 

 most of the branches, ahnost quite at their root, sometimes 

 a single polyp, sometimes two which unite together at the 

 base in order to become produced into the branch, whilst. 

 also, their spring from tin- brauch itseli', sometimes a few, 

 sometimes 2 or 3 polyps placed together (Pl. XIV, hg. 1). 

 ln the two specimens, where the inferior part of the stem 

 is bare, no polyps spring direct from it 1 . Both the stem 

 and the branches are rich in spicules. 



The polyps are cylindrical, but become somewhat 

 dilated towards the tentaeular disk (PL XIV, fig. 4). They 

 are non-retractile, and measure 8 — 9""" in length ; they have 

 a well marked posterior body measuring 4""" in length, and 

 an anterior body measuring 2.5""" in length. The tentacles 

 are about 3""" in length. Upon the body, which is pretty 

 rich in spicules, the spicules are arranged in longitudinal 

 series continued over into the aboral surface oi' the tentacles, 

 where they form a thick ridge (Pl. XIV, fig. 4), whilst the 

 lateral margins, as also the pinnules, are devoid oi' spicules 

 hut. on the other haud, are beset with nematocysts, which 

 also are observeel upon tie- somewhat arcuate oral disk. 

 The oral aperture is oblong, and has thick labiæ. 



1 There are found in almost everv speeies variatioiis of this 

 nature, and frequently still greater variatioiis, which. in most cases, 

 makes it difficu.lt. if not impossible, to determine the speeies from 

 tin- exterior ut' the Zoantkodem alone. 



13 



