444 OCEANOGRAPHY, BIONOMICS, AND AQUICULTURE. 



the deep mud are not abundant either in species or in individuals* In 

 answer to the question which of the three regions (1) the Littoral 

 zone, (2) from low water to 20 fathoms, and (3) from 20 fathoms onward, 

 is richest in small, free-swimming, but bottom-haunting, Crustacea, they 

 all replied the middle region from to 20 fathoms, which is the Laini- 

 narian zone and the upper edge of the Coralline. Professor Brady 

 assures me that nearly every other kind of bottom and locality is bet- 

 ter than mud for obtaining Ostracoda. Mr. T. Scott considers that 

 Ostracoda are most abundant in shallow water, from 5 to 20 fathoms. 

 He tells me that as the result of his experience in Loch Fyne, where a 

 great part of the loch is deep, the richest fauna is always where banks 

 occur, coming up to about 20 fathoms, and having the bottom formed 

 of sand, gravel, and shells. The fauna on and over such banks, which 

 are in the Coralline zone, is much richer than on the deeper mud 

 around them. On an ordinary shelving shore on the west coast of 

 Scotland, Mr. Scott, who has had great experience in collecting, con- 

 siders that the richest fauna is usually at about 20 fathoms. My own 

 experience in dredging in Norway is the same. In the center of the 

 fjords in deep water, on the mud, there are rare forms, but very few of 

 them, while in shallower water at the sides, above the mud, on gravel, 

 shells, rock, and other bottoms^ there is a very abundant fauna. 



Probably no group of animals in the sea is of so much importance 

 from the point of view of food as the Copepoda. They form a great 

 part of the food of whales, and of herrings and many other useful fish, 

 both in the adult and in the larval state, as well as of innumerable 

 other animals, large and small. Consequently, I have inquired some- 

 what carefully into their distribution in the sea, with the assistance 

 of Professor Brady, Mr. Scott, and Mr. Thompson. These experienced 

 collectors all agree that Copepoda are most abundant, both as to 

 species and individuals, close round the shore, amongst seaweeds, or 

 in shallow water in the Laminarian zone over a weedy bottom. Indi- 

 viduals are sometimes extremely abundant on the surface of the sea 

 amongst the plankton, or in shore pools near high water, where, 

 amongst J^nteromorpha, they swarm in immense profusion ; but for a 

 gathering rich in individuals, species, and genera, the experienced 

 collector goes to the shallow waters of the Laminarian zone. In regard 

 to the remaining, higher groups of the Crustacea, my friend Mr. Alfred 

 O. Walker tells me that he considers them most abundant at depths of 

 from to 20 fathoms. 



I hope no one will think that these are detailed matters interesting 

 only to the collector, and having no particular bearing upon the great 

 problems of biology. The sea is admittedly the starting point of life on 

 this earth, and the conclusions we come to as to the distribution of life 

 in the different zones must form and modify our views as to the origin 

 of the faunas — as to the peopling of the deep sea, the shallow waters, 

 and the land. Murray supposes that life started in Pre-Cambrian 



