482 DEPTHS OF THE OCEAN 



them with nourishment — an operation that under favourable 

 circumstances can actually be observed/ Of larger forms, the 

 numbers of which render them characteristic of these depths, two 

 sea-slugs deserve mention : a red one {Stichopus treimilus, see 

 Fig. 340), and a gray one i^Mesotlnuna intestmalis). They belong, 

 however, to a division different from the sea-slugs found in the 

 littoral zone, the distinction consisting inte7' alia in a different 

 structure of the tentacles. 



Other characteristic forms are: the brittle star AvipJiiura norvegica, 

 the sea-slugs Cuciiuiaria Jiispida and BatJiyplotes ticardi. Of higher 

 crustaceans we have the genus Munida, with the two species M. rugosa 

 and M. tenuimana, of which the latter in particular is to be met with in 

 the deepest parts of the fjords, and the prawn PontopJiilus norvegicus. 

 The mussels come next to the rhizopods in number of species, the forms 



Fig. 340. 

 Stichopus tremulus, Gunn. Reduced. (After O. F. Mtiller. ) 



most frequently found being Malletia obtusa, Portlandia hidda, P. tenuis, 

 and P.frigida, Abra longicallis and A. nitida, Kelhella miliaris, Axinus 

 flexuosus and A. ferruginosus, Ntccula tiimidula, and the species of 

 Necera. Scaphopods include three characteristic forms, namely Antalis 

 striolata, Siplwnentalis tetragona, and Cadulus aubfusifonnis, which last 

 becomes more abundant as the depth increases. Worms are represented 

 by the families Maldanidae and Terebellidse, of which latter Terebellides 

 stromi is very common, and there are also Luvibrinereis fragilis, Nephthys, 

 Aricia, etc. 



The coelenterates are represented on the mud of the deeper parts of 

 the fjords by the group of pennatuhds or sea-pens, a kind of unattached 

 coral animal. The commonest forms are Kophobeknmoii stellifeTum (see 

 Fig. 341) and Fiiniculina quadrangiilaris, though they are not so regularly 

 or abundantly distributed as the two sea-slugs already referred to, which 

 are found practically everywhere. Two species of sea -anemones 

 {Actinostola callosa and Bolocera tiiedicB) - are also universally distributed, 



1 The following are a few forms which are characteristic owing to their numbers and size : 

 the globular Saccammitia spluzrica, the rod-like ramifying Rhabdatnmma abyssoruin, and the star- 

 shaped Astrorhiza m-enaria, the test of which consists of particles of sand, the rod-like non- 

 ramifying Bathysiphon fdifo7-mis, etc. In addition there are other large forms of which I may 

 mention the species of Cristellaria, the shells of which are calcareous and consist of several cells. 



- Both these forms are found in the deep parts of the fjords, but I am not certain whether 

 they live on the mud or on the patches of harder bottom which occur here and there. 



