4 PRESIDENT'S ADDRESS. 



are known, they may be found to be in reality extremely 

 common. Another slug, the shell-bearing and carnivorous 

 Testacella Maugei, which occurs in Dorset arid was described 

 and figured in an early volume of our Proceedings (v., p. 136), 

 has been found in South Africa, but it seems probable that it 

 was introduced by man's agency. The Report of the Danish 

 Ingolf Expedition on the Crustacea Malacostraca of the deep 

 sea round Greenland, Iceland, and the Faroe Isles has lately 

 been published, and describes a large number of new species, 

 with much general information about the family. Migrations 

 of insects are not often observed in this country, though 

 many individuals do come over from the Continent, judging 

 from the numbers that sometimes appear here ; but in North 

 America huge swarms of butterflies, dragonflies, and fli3S 

 appear to move southwards in the autumn. These migrations 

 also take place elsewhere ; e.g., in the Report of the South 

 African Museum for 1915, lately issued, is an account of an 

 immense swarm of moths containing at least 20 different 

 species of Noctuidse, which appeared suddenly on a wide 

 sand belt and passed quickly on. The object or advantage 

 of these insect migrations seems difficult to determine. 

 Experiments with birds in South Africa show that they will 

 eat, when hungry, nauseous insects, which they would not 

 otherwise touch, so that the gaudy colours which give 

 warning of the nauseous taste of some insects seem to afford 

 only partial protection. Hunger undoubtedly as a rule 

 alters one's views as to what is edible, though in the case of 

 many caterpillars, they will die rather than eat the leaves 

 of any plant which is not their usual food, though one can 

 hardly think that it would really be poisonous to them in 

 most instances. Much consideration has been lately given to 

 the best means of extending our shore fisheries, which produce 

 such large quantities of valuable food. The transplantation 

 of shell fish, such as mussels, has also been encouraged, as it 

 has under certain conditions a wonderful fattening effect ; 

 and if reared in sewage -polluted feeding grounds, they can 

 be easily cleansed and rendered innocuous by a short sojourn 



