1902] The Holothurioidea of Northern Norway. 25 



Théel appears in many places in rather shallow water on the coasts. 

 All these are hitherto not found on the Norwegian coasts. 



Thus in the north of Norway nearly all the pure boreal Holo- 

 thurians, which belong to the lesser depths, are not to be found. On 

 the other hand the majority of those, which in the south of Nor- 

 way live chiefly at greater depths are to be found: Lahidoplax 

 huski is the only one of these which north of the Arctic circle is 

 found at less depths than of 100 m. Of the pure arctic species 

 Chiridota lævis lives as usual in shallow water. Myriotroclms rmUi^ 

 however, which otherwise mostly lives at lesser depths, has been 

 found here only at a depth of more than 100 m. Trochostoma bo- 

 reale and Anhjroderma jeffreysii, which otherwise also mostly live 

 at greater depths, appear here only at a depth of more than 200 m. 



In the north of Norway the Holothurian fauna of the lesser 

 depths consists of a small number of species. Those which have 

 their principal distrijbution at less depths than of 100 m. are (in 

 addition to the rare Synapta inhærens) only 5, namely the four 

 Dendrochirotæ which are common to the Arctic and the Boreal regions 

 (cf. p. 22) and also the arctic Chiridota lævis. The species, 

 which have their largest distribution at depths of more than 100 m., 

 are much more numerous, and with respect to these there is a 

 great differenee in different parts of the district in question. In 

 deeper parts of the West Fiord the Holothurian fauna is as distinctly 

 boreal as in the south of Norway. First in the fiords north of 

 69° N. do the purely arctic Holothurians begin to appear even at 

 greater depths, as the same time as some of the boreal ones disappear. 

 Similar conditions prevail in East Finmark. In these districts the 

 Holothurian fauna represent a mixture of arctic and boreal elements. 

 In shallow water the purely boreal species are certainly wanting^), 

 but there is also only one purely arctic one there viz. Chiridota 



resembles Fs. fabricii^ is nevertheless quite distmct; I have seen numerous speci- 

 mens of both these species. The specimen from Shetland (Bell 1892) is a 

 young Ps. phantapiis. Unless one has ample opportunity of making careful 

 comparisons, it is always a difficult matter to come to a definite conclusion with 

 regard to such 3'oung specimens (cf. p. 11). In this case, however, there does 

 not éxist any doubts. Bell's specimen agrees completely with young ones of 

 Ps. jphantapus from Sweden and Norway, and the locahty lies within the area 

 of distribution of this species, but far from that of Ps. fabricii. 



1) Synaptn inhærens is, however, once found at south Lofoten (p. 12) and 

 Lahidoplax huski is not seldom found in less depth than 100 m. (p. 12 and 13). 



