The Scientific Advantages of an Antarctic Expedition. 431 



Expedition in high southern latitudes, is the great rarity or absence 

 of the pelagic larvae of benthonic organisms, and in this respect they 

 agree with similar collections from the cold waters of the Arctic 

 seas. The absence of these larvae from polar waters may be 

 accounted for by the mode of development of benthonic organisms, to 

 be referred to presently. It must be remembered that many of these 

 pelagic organisms pass most of their lives in water of a temperature 

 below 32° F., and it would be most interesting to learn more about 

 their reproduction and general life-history. 



Benthos Life of the Antarctic Ocean. 



At present we have no information as to the shallow-water fauna 

 of the Antarctic continent ; but, judging from what we do know of 

 the off-lying Antarctic islands, there are relatively few species in 

 the shallow waters in depths less than 25 fathoms. On the other 

 hand, life in the deeper waters appears to be exceptionally abundant. 

 The total number of species of Metazoa collected by the " Challenger " 

 at Kerguelen in depths less than 50 fathoms was about 130, and the 

 number of additional species known from other sources from the 

 shallow waters of the same island is 112, making altogether 242 

 species, or thirty species less than the number obtained in eight deep 

 hauls with the trawl and dredge in the Kerguelen region of the 

 Southern Ocean, in depths exceeding 1260 fathoms, in which eight 

 hauls 272 species were obtained. Observations in other regions of 

 the Great Southern Ocean, where there is a low mean annual tem- 

 perature, also show that the marine fauna around the land in high 

 southern latitudes appears to be very poor in species down to a depth 

 of 25 fathoms, when compared with the number of species present at 

 the mud-line about 100 fathoms, or even at depths of about 2 miles. 



In the year 1841 Sir James Clark Ross dredged off the Antarctic 

 continent species which he recognised as the same as he had been in 

 the habit of taking in equally high northern latitudes, and he sug- 

 gested that they might have passed from the one pole to the other by 

 way of the cold water of the deep sea. Subsequent researches show 

 that, as with pelagic organisms, many of the bottom-living species 

 are identical with, or closely allied to, those of the Arctic regions, 

 and are not represented in the intermediate tropical areas. For 

 instance, the most striking character of the shore-fish fauna of the 

 Southern Ocean is the reappearance of types inhabiting the corre- 

 sponding latitudes of the northern hemisphere, and not found in the 

 intervening tropical zone. This interruption of continuity in the 

 distribution of shore-fishes is exemplified by species as well as 

 genera, and Dr. Griinther enumerates eleven species and twenty-nine 

 genera as illustrating this method of distribution. 



