33 



nosticeres saaledes: „Radialribberne flade, lave. sparsomt 

 besat med smaa runde Korn og de ydre Ender overordentlig 

 brede. Interradialrummene overstrøede med lignende Korn. 

 Armenes Bugflade nøgen. Mundpapillerne korte og spidse. 

 Tandpapillerne kugleformige. Tænderne lange, smale, ialt 

 30 — 4u. Farven paa Skiven brim. Ribberne lysere og 

 Armene gulrøde" (Fig. 18 & 19). 



Gorgonocephalus malmgrenii skal adskille sig fra 

 Gorgonocephalus eucnemis ved sine brede flade Ribber, som 

 er sparsommere forsynede med Kalkkorn; ved at den 

 mangler et sammenbængende Bælte af Kalkkorn la nus 

 Skivens Rand : ved de stærkere opbøiede Armsomme og 

 ved Armenes nøgne Bugflade. Beskrivelsen er udkastet 

 efter et 100""" stort Exemplar. Sammenligner man dette 

 med en typisk Gorgonocephalus |eucnemis, især et yngre 

 Individ, vil man vel se en saa stor Forskjel mellem dem, 

 at man herpaa kunde begrunde en ny Art, men har man 

 et tilstrækkeligt stort Materiale, vil man snart finde. at 

 disse to Arter umærkeligt gaar over i hinanden. Jeg har 

 saaledes oftere fundet hos Gorgonocephalus eucnemis, at 

 Skiveranden mellem nogle af Armene var ganske nogne. 

 medens den mellem de øvrige dels var tast, dels kun delvis 

 besat med Kalkkorn. 



Sa a vel Liitken som Lyman har allerede tidligere paa- 

 vist. at Skivens og ogsaa Ribbernes Kalkbeklædning aftager 

 med Alderen. 



Rygsidens Kalkbeklædning synes samtidig hermed at 

 være underkastede mange individuelle Variationer: ,.Man 

 træffer grovtkornede og man træffer fintkomede Individer; 

 man træffer Exemplarer. hvor Ribberne er næsten nøgne, 

 og andre, hvor Mellemrummene er det o. s. v." (Liitken '). 

 Forholdet mellem Ribbernes Længde og Bredde synes at 

 være underkastede den samme individuelle Yariation som 

 Rygsidens Beklædning. selv hos samme Individ vil man 

 finde. at den varierer: Ribberne synes dog. naar Individet 

 har naaet en vis Størrelse, at voxe stærkere i Bredden 

 end i Længden. Ribbernes og Armsommenes mere eller 

 mindre Fremstaaen synes at bero paa den Kontraktions- 

 tilstand. hvori Individet er. hvad vi allerede tidligere 

 kjender f. Ex. fra „Ribberne eller Radialskjoldene" hos 

 Ophiopleura boréalis. 



Hvis man tørrer et Exemplar af Gorgonocephalus 

 malmgrenii, vil man finde, at ogsaa hos denne Art er 

 Armenes Bugside bedækket med Kalkkorn, omend spar- 

 sommere end hos den typiske Gorgotwcephahts eucnemis. 

 Gorgonocephalus malmgrenii bør vel derfor, synes mig. ikke 

 betragtes som en selvstændig Art, men snarere som en 

 individuel Varietet af Gorgonocephalus eucnemis. 



') Addit. ad Hist. Ophiurid ., part III, pag. 66. 



Den norske Nordhavsexpedition. James A. Grieg: Ophiuroidea. 



The species is tims diagnosed: "The radial ribs flat. low, 

 sparingly beset with small round grains and the outer 

 extremities extremely broad. The interradial spaces over- 

 strewn witb similar grains. The ventral surface of the 

 arms bare. The oral papillæ short and pointed. The 

 dental papillæ clavi-form. The teeth long, narrow. 30—40 

 altogetber. The colour of the disc brown, the ribs lighter 

 in colour. and the arms yellpw-red" (fig. 18 & 19). 



Gorgonocephalus malmgrenii distinguishes itself from 

 Gorgonocephalus eucnemis, by its broad. flat ribs. which 

 are sparingly furnished with calcareous grains: by the 

 absence of a continuous belt of calcareous grains along 

 the margin of the disc: by the more elevated arm-ridges 

 and by the bare ventral surface of the arms. The 

 description is based upon a specimen 100""" large. 

 If we compare this with a typical Gorgonocephalus 

 eucnemis, especially a young individual, we will tind such 

 a great difference between them that upon it we nvight 

 base a new species, but if we have a sufficiently abundant 

 material at disposal. wc will soon observe that those 

 two species pass imperceptibly over into each other. 

 I have. thus. frequently found in Gorgonocephalus eucnemis 

 that the margin of the disc between a few of the 

 arms was quite bare, whilst between the others it was 

 partly densely, partly only partially beset with calcar- 

 eous grains. 



Liitken as well as Lyman have already previously 

 pointed out that the calcareous covering of the disc. and 

 also of the ribs. diminishes with the age. 



The calcareous covering of the dorsal surface seems 

 at same time. in correspondence therewith. to be subjected 

 to many individual variations: "Man træffer grovtkornede 

 og man træffer fintkornede Individer; man træffer Exem- 

 plarer, hvor Ribberne er næsten nøgen, og andre, hvor 

 Mellemrummene er det o. s. v." (Liitken '). The pro- 

 portion between the length and breadth of tlie ribs seems 

 to be subjected to the same individual variations as the 

 covering of the dorsal surface; even in the same individual 

 we will find that it varies; the ribs appear, however, when 

 the individual has reached a certain size. to grow more in 

 breadth than in length. The greater or smaller prominence 

 of the ridges of the ribs and arms seems to depend 

 on the state of contraction in which the individual is, 

 a circumstance we already know previously from. for 

 instance. the "ribs or radial sludds" in Ophiopleura boréalis. 



If we dry a specimen of Gorgonocephalus malmgrenii 

 we will find that also in that species the ventral surface 

 of the arms is covered with calcareous grains. although 

 more sparingly than in the typical Gorgonocephalus 

 eucnemis. Gorgonocephalus malmgrenii, should, therefore, 

 I think, not be considered as an independent species. 

 but råtner as an individual variety of Gorgonocephalus 

 eucnemis. 



') Addit. ad Hist. Ophiurid., part III. pag. 66. 



