08 
Oligochaeta or Earthworms, Pulmonate Molluscs or Slugs. 
and Snails, land Isopods or Wood-lice, certain Acari or 
Mites, and the great class of the Insects. 
Dealing first with INJURIOUS ANIMALS. BIRDS (1), 
(2), *(3} merit some amount of attention, but the fact can- 
not be emphasised too strongly that we possess extra- 
ordinarily little reliable knowledge concerning the food 
of some of our very commonest birds. Both the British 
Association and the Board of Agriculture recognise that, 
before any effective legislation can be recommended, a 
very full scientific enquiry is needed. It is necessary, 
for instance, to examine and tabulate the contents of the 
crops of certain common birds in each month of the 
year so that an opinion may be formed of the benefits or 
imjuries caused by them at the different seasons. It is. 
further necessary that some estimate should be made of 
the available food in the district where the birds were 
feeding when killed, in order to decide whether the foods 
disgovered in the crops were selected from choice or 
necessity. Much information is also desirable as to the 
food of nestling birds. Fortunately some progress is 
being made towards supplying this much needed informa- 
tion, and the Department of Economic Zoology in this 
University is performing a useful part in the work on 
behalf of the Board of Agriculture. Certain species of 
wild birds may be direct-injurious by feeding upon or 
injuring plants or parts of plants; others are indirectly 
harmful in that they may feed upon forms of animal life 
which are in themselves beneficial. Fortunately there 
are very few species of birds which we may declare to 
be wholly destructive and, of these, the House Sparrow 
and. Wood Pigeon are the most important. The Black- 
bird also appears to have very little utility in the eyes. 
of man, and is a most persistent devourer of fruit. On 
the other hand, there is a large number of birds whose 
role is doubtful; in many cases we lack adequate knowl- 
edge to judge fairly as to their feeding habits, but they 
all appear to have a good deal of utility in their favour. 
Among these may be cited the Song Thrush, Great and 
Blue Tit, Greenfinch, Chaffinch, Rook, Robin, Linnet, 
Yellow-hammer, Skylark, Starling, Woodpeckers and 
* The numbers in brackets refer to the literature which is 
listed at the end of this series of lectures. 
