DE. P. H. CAEPENTER ON SOME ARCTIC COMATUL^. 57 



name ; and he was strengthened in this opinion by his comparison 

 of the two youngest individuals from Jau Mayen and also of the 

 Pentacrinoids with the descriptions of A. Sarsii and its larva. 

 He expressed his conviction, therefore, " dass unter Antedon 

 prolixa, Sladen, nur ausgewachsene Exemplare von A. Sarsii, 

 welche bislang uoch nicht erschopfend beschrieben waren, zu 

 verstehen sind." 



Under these circumstances it seemed desirable that the cha- 

 racters of these two species should be re-investigated, and direct 

 comparisons made of all the available material. The types of 

 Ant.prolioaa are in the National Collection, while the two examples 

 of it obtained by the ' Varna ' in the Kara Sea are still in my 

 keeping, together with numerous speeimeas of A. Sarsii {tenella) 

 obtained by the ' Porcupine,' ' Triton,' ' Blake,' ' Willem Barents,' 

 &c. ; while, thanks to the kindness of Dr. von Marenzeller, I 

 have been enabled to compare these individuals with the two 

 original 'Tegetthoff' specimens, and also with all those obtained 

 by Dr. Pischer at Jan Mayen. Careful investigation of all this 

 material has convinced me that Antedon prolixa is a good species, 

 and quite distinct from A. tenella. Both the two ' Tegetthoff ' 

 specimens and also Sladen's types are immature individuals, 

 Pischer's largest example from Jan Mayen (PI. 11. fig. 4) being 

 the first fully grown one yet obtained. Since seeing this, too, I 

 have no longer any doubt that the Antedon Jiystrix which was 

 dredged by the ' Porcujjine ' and ' Triton ' in the cold area of the 

 Paroe Channel, and by the Norwegian North- Atlantic Expedition 

 from 743 fathoms near Spitzbergen *, should also be referred to 

 A. prolixa, a possibility which I mentioned when discussing A. 

 Jiystrix in the ' Challenger ' Eeport f. 



The two specimens dredged by the ' Porcupine ' in 1869 thus 

 prove to be the first discovered individuals of A. prolixa ; but 

 neither they nor those from the ' Tegetthoff' were recognized as 

 new to science at the time ; and the species was first described by 

 Sladen from the less mature individuals brought home by Sir 

 Greorge Nares's Arctic Expedition of 1875-76. 



The essential points of difference hQiween Antedon prolixa andi 



* This is the Antedon celtica mentioned by Nansen in his ' Bidrag til Myzos- 

 tomernes Anatomi og Histologi,' Bergen, 1885, p. 6. I am indebted to the 

 kindness of Dr. Nansen for specimens of the type, dredged by the ' Voringen. 



t Op. cit. p. 167. 



XINN. JOTJEN. — ZOOLOGY, YOL. XXIY. 5 



