300 Mr. J. H. Gurney, Jun., on the Ornithology of Algeria. 



140. Anas acuta, Linn. 

 Once in the market. 



Pintail. 



141. Larus RiDiBUNDUs, Linn. Black-headed Gull. 



As Black-headed Gulls were very numerous in the harbour 

 of Algiers in February, I was surprised to find that they had all 

 left on my return from the Sahara in the spring. I conclude 

 they had gone to Halloula, or some other lake. 



Although modern researches have decided that some birds 

 migrate laterally [i.e. from south-east to north-west, or vice versa) 

 the majority of our vernal migrants come to England from due 

 south. Hence Northern Africa is peculiarly interesting to the 

 British ornithologist. North even of the great Atlas chain, 

 countless Willow- Wrens and Blackcaps throng every hedge- 

 row. I think it is no exaggeration to say that I saw enough of 

 these two species to account for the multitudes which annually 

 quit Great Britain ; but, with a few such exceptions, our birds 

 of passage go further south than the Atlas. Towards the end 

 of April I began to notice Philomela luscinia, Phylloscopus sibi- 

 latrix, Anthus arboreus, Muscicapa atricapilla, Turtur auritus, 

 restlessly pressing northward. The same birds are migratory 

 in the two countries; and it was interesting to observe how 

 nearly they preserved the same order of precedence inter se. 

 The difference in the time of their arrival is in many instances 

 inconsiderable, as will be seen from the following comparative 

 table. It would require a number of observations, extending 

 over a series of years, before we could use such data to get at 

 the speed at which they travel. 



