22 



Ophiacantha bidentata (Retz.) Ljungman. 



1805. Asterias bidentata. Retzius, Dissertatio, pag. 33. 

 1817. Ophiura retzii, Nilsson. Oollectanea Zoologiæ Scandi- 

 navian, pag. 15. 

 1842. Ophiacantha spinulosa, Mull. & Tr.. System der 



Asteriden. pag. 107. 

 1842. Ophiocoma arctica. Miill. Å- Tr.. ibid. pag. 103. 

 1844. Ophiocantha gronlandica, Miill. & Tr., Beschreibung 



neuer Asteriden. pag. 183. 

 1852. Ophiocoma echinulata. Forbes, Sutherlands Journ. 



Vov. Baffins Bay. vol. II, App. 

 1858 Ophiacantha spinulosa. Lutken. Addit. ad Hist. 



Ophiurid., part I, pag. 65. Tab. II, 



fig. 14. 

 1865. Lyman, 111. Oat. Mus. 



Comp. Zool., vol. I. no. 1. pag. 93. 



Fig. 6 & 7. 

 1371. — bidentata, Ljungman. Ofversigt Kongl. 



Akadm. Forhandl., pag. 652. 

 1877. spinulosa. Duncan & Sladen, Ann. & 



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



pag. 466. 

 1881. id. Memoir on the Echin- 



odermata of the Arctic Sea etc. 



pag. 68. Tab. IV. fig. 11—13. 

 1892. bidentata, Jeffrey Bell. Catalogue of 



British Echinoderms. pag. 127. 



Verril! har delt Ophiacantha bidentata i t<> Arter, 

 hvoraf den ene. der skulde være identisk med Retzius's 

 Art, kun kunde gaa ned til 300—400 Fv. Dyb, medens 

 den anden, som han har kaldt Ophiacantha fraterna, er 

 en ægte Dybvandsform, som blot forekommer paa de store 

 Havclyb (900— 1600 F v.) 1 ). Til den sidste Art skulde 

 altsaa foruden Albatross-Exemplarerne en Del Dybvands- 

 exemplarer fra Blake's. ( !hallenger's, Bulldog"s og Porcu- 

 pine's Expeditioner høre. Hvad der skulde adskille disse Arter, 

 er. at Ophiacantha fraterna er mindre end Hovedformen, 

 som kan have en Skivediameter af indtil 15"""; imidlertid 

 er dog en saadan Storrelse meget sjelden, hyppigst har 

 Skiven kun en Diameter af 9 — 12""", eller er af samme 

 Storrelse som Ophiacantha fratema's. 



Fra Skivens Bedækning kan man heller ikke hente 

 sikre Artsmærker. I Bergens Museums Echinodermsamling 

 tindes 5 Exemplarer af Ophiacantha bidentata. tagne af 

 Blake paa 1247 Favnes Dyb, de maa altsaa ifolge Verrills 

 egne Ord betragtes som typiske Repræsentanter for hans 

 Ophiacantha fraterna. Sammenligner man disse med 

 Grundvandsexemplarer fra Finmarken, vil man ikke kunne 

 finde nogen nævneværdig Forskjel i Skivens Bedækning 

 Ophiacantha fraterna skal dernæst have grovere Armpigge 

 finere og spidsere Fodpapiller (tentacle scales) og skarpe. 



') Results of the explorations made by the steamer Albatross in 

 1883, pag. bi:< (4r!i. 



Ophiacantha bidentata (Retz.) Ljungman. 



1805. Asterias bidentata, Retzius. Dissertatio. pag. 33. 

 1817. Ophiura retzii. Xilsson, Collectanea Zoologiæ Scandi- 



naviæ, pag. 15. 

 1842. Ophiacantha spinulosa, Miill. & Tr.. System der 



Asteriden. pag. 107. 

 1842. Ophiocoma arctica, Miill. & Tr.. ibid. pag. 103. 

 1844. Ophiocantha gronlandica, Miill. et Tr.. Beschreibimg 



neuer Asteriden. pag. 183. 

 1852. Ophiocoma echinulata. Forbes. Sutherlands Journ. 



Voy. Baffins Bay. vol. II. App. 

 1858. Ophiocantha spinulosa. Lutken, Addit. ad Hist. 



Ophiurid., parti. pag. 65. Pl. II. 



fig. 14. 

 1865. Lyman. 111. Cat. Mus. 



Comp. Zool.. vol. I. no. 1. pag. 93. 



Figs. 6 & 7. 

 1871. bidentata. Ljungman, Ofversigt Kongl. 



Akadm. Forhandl., pag. 652. 

 l s 7 7. spinulosa, Duncan å Sladen. Ann. & 



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



pag. 4(56. 

 1881. id. Memoir on the Echin- 



odermata of the Arctic Sea &c, 



pag. 68. Pl. IV. figs. 11—13. 

 1892. bidentata. Jeffrey Bell. Catalogue of 



British Echinoderms. pag. 127. 



Verril] has divided Ophiacantha bidentata into two 

 species, of which the one, supposed to be identical with 



Retzius's species. can only reach to a depth of 300 — 400 

 fathoms. while the other, which he has named Ophiacantha 

 fraterna is a genuine deep-water tonn that is only met 

 with in the great ocean depths (900 — 1600 faths.) x ). 

 To the last-named species should therefore belong. besides. 

 the Albatross specimens, a number of deep-water specimens 

 from Blake's. Challengers, Bulldog's and Porcupine's expe- 

 ditions. What destinguishes those species is. that Ophia- 

 cantha fraterna is smaller than the typical form. which 

 may have a disc-diameter of up to 15""", but such a size 

 is. however, very rare; most frequently the disc has a 

 diameter of 9 — 12""" or the same size as Ophiacantha 

 fraternes. 



Neither can we obtain from the covering of the disc 

 decisivc characteristic features. In the collection of Echin- 

 oderms in Bergens Museum. 5 specimens of Ophiacantha 

 bidentata are found, obtained by the Blake at a depth of 

 1247 fathoms: they must. therefore, according to VerrilFs 

 own statement, be considered as typical representatives of 

 his Ophiacantha fraterna. If we compare them with speci- 

 mens from shallow depths from Finmark we are unable 

 to observe any difference, worth the name, in the covering 

 of the disc. Ophiacantha fraterna is further said to have 



') .Results of the explorations made by the steamer Albatross in 

 1883, pag. ."it". (43). 



