330 KEPORT— 1894. 



hose can be played upon masses of it almost indefinitely without dissolving 

 it. The fauna of this zone is, in our district, quite peculiar and character- 

 istic. In its shallower parts, about 50 fathoms, it contains great numbers 

 of living and dead TurriteUa terehra, upon many of which are attached one, 

 two, or three specimens of the little red anemone Sagartia Herdmani, 



Fig. 2. — Sagartia Herdmani (Haddon). 



Haddon. In its deeper parts, up to 80 fathoms, are found Calocaris 

 MacandrciP, Ilyalincecia hihicola, a small Lumbriconei-eis, Panthalis 

 Oerstedi, Lijjobranchius Jeffreysii, Brissopsis lyrifera, Aviphiura Chiajii, 

 and Isocardia cor. Great quantities of large sausage-like muddy tubes, 

 formed of stratified layers of interlacing threads of mucus in wliich the 

 mud particles are closely entangled, are brought up in the dredge. These 

 are almost certainly the tubes of Panthalis Oerstedi, and the living annelid 

 has several times been found in the tubes, but most of those we dredge 

 up are empty, and the tubes are certainly far more numerous than the 

 worms. Possibly the explanation is that the Panthalis forms a tube as it 

 • lies in the mud, and then when it moves away leaves its tube behind it 

 (one can scarcely imagine the animal dragging such a tube through this 

 tenacious deposit), and after a time forms another in a new situation. 



These are the leading conclusions we have come to so far in regard to 

 the distribution of submarine deposits in our area. Two further questions 

 now present themselves : first, the biological one — the effect upon the 

 fauna ; and secondly, the geological one — the origin of the deposits. In 

 regard to the importance of the nature of the bottom to the animals living 

 upon it there can be no doubt. Probably the nature of the deposit is the 

 most important of the various factors that determine the distribution of 

 animals over the sea-bottom within one zoological area. It is certainly 

 more important than mere depth ; a muddy bottom will support a similar 

 fauna at ten fathoms in one place and at fifty fathoms in another. Pro- 

 bably the most important influence in the environment of a lower animal 

 is its food, and once beyond the narrow sub -littoral zone in which algse 

 flourish — and to which, of course, certain pliytophagous animals must be 

 restricted — it is probably chiefly the nature of the bottom which deter- 

 mines the food.^ Many animals feed upon the deposit, others browse upon 

 the polj'zoa and zoophytes which can only attach themselves and grow 

 where there are sufficiently large objects, such as shell valves, from which 

 they can get the necessary stability ; while others, again, feed upon their 

 neighbours, which subsist on the deposit or are attracted by the zoophytes, 

 <tc. ; for example, soles are frequently caught upon ground (known to 

 fishermen as ' sole ground ') where Flustra foliacea lives in abundance, and 

 the probable connection is that the fish are dependent upon the numerous 

 a,mphipoda and other small animals which frequent the tufts of Flustra. 

 The same locality may vary so much from time to time in the temperature, 

 the salinity, and the transparency of the water, that it is probable that 



' The only food supply quite independent of the bottom is dead pjankton, from 

 the water above, which may reach the bottom uneaten. 



