1921 .] Recently published Ornithological Works. 733 
Bretscher on Bird-migration in Middle Europe. 
[Der Vogelzug in Mitteleuropa. Mit 16 Karten und vielen Tabellen. 
Von K. Bretsclier. Pp. 1-162. Innsbruck (Wagnerschen Univ. 
Buchdruck.) 1920. 8vo.] 
In this separately-published memoir Mr. Bretscher en¬ 
deavours to trace out the migration routes in Switzerland 
and the neighbouring countries by an elaborate analysis of 
all the available data. The first two chapters, comprising 
more than half the work, deal with the spring and autumn 
migration in Switzerland. These are followed by an 
analysis of the spring migration in Alsace-Lorraine, Bruns¬ 
wick, and Hungary, and in the final chapter the influence 
of temperature is discussed. 
The general method employed in the case of Switzerland 
is to divide the country into seven geographical areas, and 
by plotting down the date of observation, according to the 
areas and the date of the u Zugsmittel 99 or culmination of 
the migration-time, to discover by what route the various 
species enter the country. In the case of the spring 
migration the general conclusion appears to be that most 
of the migrating birds enter Switzerland at the south-west 
corner of the Lake of Geneva or in the north-west over the 
Jura, and that, with the exception perhaps of the Swallow, 
no birds cross the high ranges of the Alps from the south. 
The paper is a long one and full of details and conclusions 
which it is impossible to summarize in a short notice, and 
our only fear is that the data used are hardly sufficient to 
warrant some of the conclusions arrived at. 
Chapin on new African Birds. 
[Descriptions of four new birds from the Belgian Congo. By James 
T. Cbapin. Amer. Museum Novitates, no. 7, 1921, pp. 1-9 ; 3 figs.] 
This is the fifth preliminary paper on the results of the 
author's expedition to the Belgian Congo on behalf of 
the American Museum of Natural History, and contains 
descriptions of the following new forms from the Ituri and 
Upper Uele districts :—Astur toussenellii canescens , Colius 
ser. xi.— vol. hi, 3 c 
