526 Dr. A. L, Thomson : Results oj a Study of [Ibis, 
particular area is accordingly significant only when it can be 
shown that the species tends to yield a good proportion of 
records under circumstances such as are prevalent there. 
It is therefore thought probable that promiscuous marking 
has now had a sufficient trial in the British Isles and that it 
will be found, more especially when summarised results of 
the 44 British Birds 55 scheme have also been published, that 
the necessary data are now available for the formulation of 
more definite plans of campaign for concentrated action. 
If possible, definite problems should be kept in view and 
the work of marking should be systematically directed to 
the accumulation of relevant facts. The Lapwing, to give a 
single instance, would assuredly yield results of the 
highest theoretical interest if it could be marked simul¬ 
taneously and in a large number of selected districts—say, 
the north of Scotland, the south of England, Ireland, 
Holland, a district of France, and a district of Norway. 
XIII.— REFERENCES. 
{References not relating to the marking method are given 
in the text.) 
(1) Baldwin, S. Prentiss (1919).—“ Bird-Banding by Means of Syste¬ 
matic Trapping.” (Abs. Proc. Linn. Soc. New York , xxv., 
23.) 
(2) Bartsch, Paul (1904).—“Notes on the Herons of the District of 
Columbia.” ( Smiths. Miscel. Coll., xlv., 104.) 
(3) Cole, Leon J. (1902).—“Suggestions fora Method of Studying 
the Migrations of Birds.” ( Third Report of the Michigan 
Academy of Science, 67.) 
(4) —— (1909).—“The Tagging of Wild Birds as a Means of 
Studying their Movements.” (Auk, xxvi., 137.) 
(5) - (1910).—“ The Tagging of Wild Birds : Report of Progress 
in 1909.” ( Auk , xxvii., 154.) 
(6) Douglas, S. R. (1917).—“An Experimental Investigation of the 
Migration of Woodcock breeding in the West of Ireland.” 
\Proc. Zool. Soc. London, 1917, 159.) 
(7) Hamilton, John (1908).— (Field, 1908, 717 & 745.) 
(8) Herman, Otto, and Schenk, Jakob (1909 et seq.). — (Aquila, 1909, 
34): and subsequent periodical reports. 
