404 Prof. M' In tosh on the 



on their respective sites, but the latter are often almost 

 imbedded in it. The witch [Pleuronectes cynoglossus) is 

 partial to muddy ground, mud is the home of the hag-fish, 

 and even the delicate young flounders, on descending after 

 their pelagic existence and metamorphosis to the bottom, skim 

 through and hide (all but the eyes) in it along oar muddy 

 shores. Referring to the tidal and adjoining area, the con- 

 clusion then (1871) was: — "In general, muddy ground is 

 found to be much more productive in marine life of all kinds 

 than where the rocks, sea- weeds, and sands are pure." The 

 barrenness of such regions in the Mediterranean, therefore, was 

 not proved to be due to the muddy character of the water 

 per se. The greatly extended researches of a quarter of a 

 century have only confirmed these opinions. 



This question of the muddy deposits has again, and quite 

 recently, been brought forward by Dr. John Murray, who, in 

 the ' Challenger ' publications *, established what he calls a 

 mud-line, which he fixes everywhere at or about 100 fathoms. 

 He considers this line the great feeding-ground of tlie ocean, 

 citing, in proof, the capture of myriads of young and adult 

 crustaceans, many of them phosphorescent, and nearly all of 

 the red or brown colour characteristic of deep water. These, 

 again, he says, furnish food for migratory fishes, such as the 

 herring and the salmon f, while the stomachs of whales are 

 crowded with cuttlefishes and crustaceans from considerable 

 depths. His views were criticized last year by Prof. Herd- 

 man in his address to the Zoological Section of tiie British 

 Association, and he differed so mucli as to hold that the deep- 

 sea mud supports " a comparatively poor fauna as compared 

 with other shallow-water de])osits." He contrasts the hauls 

 of small trawls in shallow water with those of the ' Chal- 

 lenger ' in the deep-sea mud, and shows that the number of 

 species and genera is greater in the former. It must be 

 borne in mind, however, that some of the finest fishing- 

 grounds are those in muddy areas, which abound in marine 

 life of all kinds. The selection of more or less pelagic crusta- 

 ceans as the test of the correctness of Dr. Murray's theory 

 appears to be of doubtful import, though the latter himself is 

 perhaps responsible for it. Such forms often fill the tow- 

 nets over pure sand, or in midwater or near the surface far 

 from mud. They are, indeed, found in great numbers under 

 very diverse circumstances. The more minute, however, 



* ' Deep-sea Deposits/ p. 184 et sea., 1891 ; Summary, vol. ii. p. 1433, 

 1895. 



t It would be interesting to give in detail the food of the salmon iu 

 the offshore waters. 



