466 ON THE FAUNA AND BOTTOM-DEPOSITS NEAR THE 30-FM. LINE 



on others. Its distribution depends almost entirely upon the dis- 

 tribution of Fecten opercular is, as will be seen clearly from the tables. 

 Owing to its gregarious habits P. opcrcvlaris is very much more 

 abundant in some hauls made upon a particular ground than in others, 

 and a study of the records of the individual hauls brings out the 

 connection between the star-fish and tlie mollusc even more clearly than 

 the summarised results given in Table VI. 



Habits. A. ruhens creeps on the surface of the sea-bottom, and appears to he almost 

 independent of the nature of the bottom-deposit. It feeds very largely upon molluscs 

 (Forbes, No. 22, p. 87), and on the grounds described in this jiaper almost entirely upon 

 Pccten opercularis. I have directly observed the remains of P. opcrcularis in the mouth of 

 the star-fish. An account of the method adopted by this and allied species in opening 

 various kinds of molluscs has been given by Schiemenz (No. 104). 



Distribution. Geographical. Bell (No. 7) gives "Eastern side of North Atlantic 

 (Senegal to Finmark), Japanese Seas. Presence in Arctic Ocean uncertain, in Mediter- 

 ranean very doubtful." Ludwig (No 70) does not include A. ruhens amongst Mediterranean 

 sj)ecies. It is generally distributed in the Kattegat (Petersen) and Baltic (Mol)ius). 



Depth. 0-110 fathoms (Bell); to 337 fathoms (Mbbius and Biitschli, No. 88). 



Bottom-deposit. The species is recorded on grouuds of every texture, from rocky ground 

 to mud. 



Asterias glacialis (Chart VI.). The distribution of A. glacialis on 



the Eddystone grounds is almost exactly the same as that of A. 



rubens, and, like that species, it is always most abundant in those 



places where Pccten opercularis is found in numbers. It is noteworthy, 



however, that A. glacialis was never taken in the hauls south of 



Bolt Head nor on the Prawle Point Ground. The most easterly 



station was haul 60 (three miles south-west of Bolt Tail). The 



importance of this point will be apparent when the geographical 



distribution of the species is discussed. 



Habits. A. glacialis is similar in its habits to A. rubens, and, like that species, lives 

 largely upon molluscs. It is perhaps rather more given to climbing than A. rubens. In 

 addition to molluscs, A. glacialis feeds upon almost any animal which it can capture, as 

 well as upon dead fish, etc. (Ludwig, No. 70). Cuenot (No. 18) found a specimen feeding 

 upon Portunus puber, and in the aquarium at Plymouth a specimen was found eating 

 Polyhius Henslowii. 



Distribution. Geographical. The distribution of Asterias glacialis 

 is discussed in detail by Ludwig (No. 70, p. 393). It is a southern 

 species, common in the Mediterranean, and extending along the eastern 

 shores of the Atlantic from Cape Verde Islands to Norway as far north 

 as the coast of Finmark, Ludwig is doubtful as to whether the species 

 really extends to Arctic Seas. A point of great interest in its distribu- 

 tion is its absence from the eastern portion of the English Channel, and 

 from the southern and eastern part of the North Sea. " In the North 

 Sea it is not known either on the east coast of England nor on the east 

 coast of Scotland (Norman, 1865); it is also absent from the Belgian, 

 Dutch, and German Coast, and the neighbouring islands. It is found, 

 however, in the north-east part of the North Sea (Meissner and Collin) 

 and between Scotland and Norway (Mobius and Biitschli). From there 



