492 DEPTHS OF THE OCEAN 



not on soft clay bottom ; all the individuals from stations in the 

 open North Sea at considerable depths were very much lighter 

 in colour and much larger than those taken along the Norwegian 

 and British coasts. A good idea of the enormous quantities in 

 which this form sometimes occurs was afforded by a haul with 

 the dredge off Aberdeen, in 25 metres of water (temperature 

 10.26° C), where they must have literally covered the bottom, 

 and the same remark applies to the west coast of Jutland. In 

 some localities we met with numbers of Brissopsis lyrifera, 

 which prefers as a rule clay bottom in deep water at a tem- 



FiG. 347- 

 Ophiura ciUaris, L. Reduced. 



perature of 6° or 8^ C, though occasionally specimens may be 

 found on sand. Everywhere, throughout the whole area 

 examined, there were the two brittle-stars Ophiopholis aculeata 

 and Ophiothrix fragilis, as well as the starfish Liddia sarsi, 

 which are numerous here and there, but cannot be called 

 characteristic forms. More local, though plentiful in places, 

 were sea-slugs {Cucumaria elongatd), which were met with at 

 two stations, together with Brissopsis, on muddy bottom in 

 about 50 metres, at a temperature of approximately 8° C.^ 



^ Of other echinoderms found at a few stations, in smaller quantities, I may mention Ophiura 

 albida (only at one or two stations in the neighbourhood of the Danish coast and one station off 

 Aberdeen in 25 metres) and O. sarsi, Aniphiiira filiformis {chiajeil), Ophioden sericeum (many 

 young-stages in young-fish trawl east of Aberdeen in 62 metres, temperature 8'4° C, and also 

 from the Norwegian depression), Asterias 7iiiillcri, Solaster papposus (only from the edge of the 



