1902] The Holothiirioidea of Northern Norway. 21 



17. Trochoderma elegans Théel. 



I have now before me a specimen of this spedes whicli is new 

 in the Norwegian fauna; it was obtained by G. 0. Såes at 

 Mortensnes in the Varanger Fiord 70° 4' N.; as to the depth at 

 which it was found, I have no particulars. In other places it has 

 been found at a depth of 10 — 220 m.^) 



Of the above 17 species there are three, which Ludwig (1900) 

 does not mention as existing in the region discussed in this treatise, 

 viz. Lahidoiilax busJci, Myriotrochus vitreus and Trochoderma elegans. 

 Lahidoplax has, however, as I have shown above, long ago been 

 found in these regions^ though it has wrongly been called Synapta 

 inhærens; and Myriotrochus (Oligotrochus) vitreus is mentioned by 

 M. Såes as existing in Lofoten, but it has afterwards wrongly been 

 considered to be identical with M. rinJcii. The species which are 

 really new in this district are, besides Trochoderma elegans, the 

 genuine Synapta inhærens små the genuine 3Iyriotrochus r inJcii. Of 

 these three Myriotrochus rinkii is to be found in East Finmark, as 

 well as in the most north ern fiords of West Finmark ; Trochoderma 

 elegans is known only in the most eastern and most arctic part of 

 the district (Varanger Fiord), Synapta inhærens in its most southern 

 and warmest part (south Lofoten). 



On the other hand, I have left out three species which, accor- 

 ding to Ludwig, should be met with all the way up to the 69° 

 N. viz. Cucumaria elongata DiJB. & Koe., C. lactea (Foeb.) and 

 Thyone fusus (0. F. Mijll.). The reason is that Ludwig's statement 

 is due to a geographical mistake. Geieg (1898) describes the 



^) As will be seen from the note p. 16, the statenients made by Stux- 

 BEKG (1880) and Ludwig (1900) regarding the existence of this species in the 

 Sea of Siberia, even East of the Sea of Kara, are founded npon a mistake 

 made hj Stuxberg. It is, nevertheless, by no means improbable that it should 

 be found there, for it is apparently very widely spread in the Arctic Ocean, 

 but on account of its diminative size it is easily overlooked. During three of 

 the more recent Swedish Arctic expeditions, specimens have been found in 

 various locahties in Spitzbergen (Nathorst's expedition 1898) and in East G-reen- 

 land (Nathorst's expedition 1899, Kolthoff's 1900). 



