35 



Gorgonocephalus agassizii (Stimpson) Lyman. 



(Tab. III, fig. 20 & 21). 



1819. Gorgonocephalus arcticus. Leach, Ross's Voyage of 



Discovery in H. M.S. „Isabella" 

 and «Alexander", vol. IIApp., 

 No. IV, pag. 178. 



1841. Euryale scutatum, Gould, Invert. of Massachus- 



setts. pag. 345. 



1853. Astrophyton agassizii, Stimpson, Syn. Mar. Invert. 



Gr. Manan, Smithson. Contrib., 

 vol. VI pag. 12. 



1865. Lyman. 111. Oat. Mus. Comp. 



Zool., vol. I, No. 1. pag. 186. 



1869. Liitken, Addit. ad Hist. 



Ophiurid.. part III, pag. 66. 



1877. arcticum, Duncan & Sladen, Ann. & 



Mag. Nat. Hist., ser. 4, vol. XX 

 pag. 468. 



1877. agassizii, Lyman, Proceed. Boston 



Soc. Nat. Hist,, vol. XIX 

 pag. 102. 



1881. — Duncan & Sladen, Memoir 



on the Echinodermata of the 



Arctic Sea etc, pag. 69. 

 Tab V, fig. 1—6. 



1882. Gorgonocephalus agassizii. Lyman, Eeport on 



the Ophiuroidea, Chall. Exp. 



Zool, vol. V, part 14. 



pag. 264. Tab. XXXV, fig. 26. 



Tab. XXXVI. 

 1886. Fischer, Die osterreich. 



Polarstation, Jan Mayen, 

 Bd. III, pag. 37. 



Det mindste Exemplar af denne Art, som Nordhavs- 

 expeditionen erholdt (Stat. 124), havde en Skivediameter af 

 4.5""". Skivens Bygside med Undtagelse af et lidet Parti 

 pa a begge Sider af Armene, li vor der fandtes en liden 

 Pordybning eller Spalte, var tæt og ensformigt granuleret 

 med større og mindre runde eller ovale Korn og Plader 

 (Fig. 20). Pladerne, Lymans „primary plates, each en- 

 circled by a superimposed list of grains" (pag, 252, 

 Tab. XXXVI, fig. 3g), har en hvælvet Overflade og er 

 ligesom Kornene fint granulerede (Fig. 21). Lignende 

 Korn tindes ligeledes paa Armenes Bygside. hvis basale 

 Del især er tæt bedækket. Skivens Bugside er ogsaa for- 

 synet med Kalkkorn, omend sparsommere end Bygsiden ; 

 Plader synes derimod omtrent ganske at mangle paa Bug- 

 siden. Som allerede af Lyman paapeget, minder Bygsidens 

 Beklædning meget om den hos unge Individer af Ophiopholis 

 aculeata. 



De ovenfornævnte ti Fordybninger ved Armenes 

 Basis strækker sig fra Skiveranden ca. 0.9"""' indover mod 

 Skivens Midte; deres største Bredde er omtrent halv saa 



Gorgonocephalus agassizii (Stimpson) Lyman. 



(Pl. III, fig. 20 & 21). 



1819. Gorgonocephalus arcticus. Leach, Boss's Voyage of 



Discovery in H.M.S. "Isabella" 



and "Alexander", vol. II App. 



No. IV, pag. 178. 

 1841. Euryale scutatum, Gould, Invert, of Massaclms- 



setts, pag. 345. 

 1853. Astrophyton agassizii, Stimpson, Syn. Mar. Invert. 



Gr. Manan, Smithson. Contrib., 



viil. VI pag. 12. 

 1865. Lyman. 111. Cat. Mus. Comp. 



Zool., vol. I, No. 1. pag. 186. 

 1869. Liitken. Addit. ad Hist. 



Ophiurid, part III, pag. 66. 

 1877. arcticum. Duncan & Sladen, Ann. & 



Mag. Nat. Hist,, ser. 4, vol. XX 



pag. 468. 

 1877. agassizii, Lyman, Proceed. Boston 



Soc. 'Nat. Hist., vol. XIX 



pag. 102. 



1881. — Duncan & Sladen. Memoir 



on the Echinodermata of the 

 Arctic Sea etc. pag. 69. Bl. X, 

 fig. 1—6. 



1882. Gorgonocephalus agassizii. Lyman, Report on 



the Ophiuroidea, Chall. Exp. 

 Zool., vol. V, part 14, 

 pag. 264. Pl. XXXV, fig. 26. 

 Pl. XXXVI. 

 1886. — Fischer, Die osterreich. 



Polarstation, Jan Mayen. 



Bd. III. pag. 37. 



The smallest specimen ol this species obtained by 

 the North Atlantic Expedition (stat. 124) had a disc- 

 diameter of 4..V"". The dorsal surface of the disc, except 

 a small portion on both sides of the arms, where a small 

 cavity or fissure was observed, was densely and uniformly 

 granulated with larger and smaller round or oval grains 

 and plates (fig. 20). The plates, Lyman's "primary plates, 

 each encircled by a superimposed list of grains" (pag. 252, 

 Pl. XXXVI, fig. 3 g), have an arcuate outer surface and 

 are, like the grains, finely granulated (fig. 21). Similar 

 grains are likewise found on the dorsal surface of the arms. 

 whose basal portion especially is densely covered. The 

 ventral surface of the disc is also furnished with calcareous 

 grains, although more sparing] v than on the dorsal surface; 

 plates seem, on the other hand, to be almost completely 

 absent on the ventral surface. As already remarked by 

 Lyman, the covering of the dorsal surface reminds much of 

 the same feature in young individuals of Ophiopholis aculeata. 



The above-named ten eavities at the base of the 

 arms extend from the margin of the disc about 0.9""" inwards, 

 towards the middle of the disc; their greatest breadth is 



