THE OCEAN FOOD SUPPLY 333 
Fifteen rich hauls with trawl and dredge in depths varying 
from 40 to 300 fathoms enabled a large collection of the benthos 
to be made. A striking feature of the marine fauna of the Ant- 
arctic is the extraordinary wealth of individuals, while the variety 
of forms does not appear to be very great. Also the large size 
to which some species attain as compared with their relatives in 
warmer seas is very marked. 
This is, however, not the case with animals which require 
carbonate of lime, for the secretion of limy skeletons by members 
of the benthos seems to be at a minimum in the cold Antarctic 
waters. The shells of molluscs are small and fragile. Some sea- 
snails have no lime in their shells at all. 
It requires the warm tropical seas for animals with calcareous 
skeletons to reach their vigorous growth. 
Many of the bottom’animals crawl over the sea floor and pass 
the nutritious mud through their digestive organs after the man- 
ner of earth worms; others take up a stationary vertical posi- 
tion, and by means of tentacles waft the falling diatoms into their 
mouths before they have time to reach the bottom. 
Almost every trawl brought up quantities of large siliceous 
sponges covered with glassy spicules. 
Good collections of sea-anemones, worms, urchins, starfishes, 
crustacea, sea-spiders, molluscs, and fishes were obtained. The 
collection of fishes has already been found to contain some new 
genera and several new species. There can be no doubt that 
many new forms will be found among the other groups. 
Considerable quantities of three species of Cephalodiscus 
were obtained. ‘These animals are of interest because they show 
signs of a distant relationship to the vertebrates, though their 
mode of life is very dissimilar. The minute individuals live to- 
gether in colonies, and build up a gelatinous tree-like house. 
The young forms of Cephalodiscus are very imperfectly 
known, and it is hoped that larval stages may be found among 
the material brought home, so that further light may be thrown 
upon the development of these curious animals. 
In the last volume of the Biological Reports it is proposed to 
review the known marine benthos of the continental shelves of 
the globe in regard to its distribution in time and space. One of 
the objects of this enquiry will be to ascertain, as far as our pres- 
ent knowledge will permit, if there has been any tendency on the 
