ACEOCEPHALUS PALUSTRIS. 403 



13th. I was away till July 21st, when the birds, old and young, 

 were still in the osiers. 



1898, June^th. — Birds paired, and male singing, in the usual 

 place. The osiers were still neglected and overgrown, but there 

 were open places here and there. On 20th I found a nest with 

 five eggs ; on 21st a second with one egg, and a third with four. 

 Two of these were in meadow-sweet, the other in the osiers. 

 From one of these nests the eggs gradually disappeared between 

 June 25th and 28th, when I cut it out of the meadow-sweet, and 

 found the egg of a Cuckoo buried under a fresh lining. This 

 nest is now in the Oxford Museum, and I believe this is the only 

 case on record in this country of a Cuckoo laying in a Marsh- 

 Warbler's nest. The explanation probably is that the Cuckoo 

 was very late with her egg, and the Marsh-Warbler's nest was 

 the only one handy which contained freshly laid eggs. As it was 

 clear that the removal of the Marsh-Warbler's eggs was not due 

 to any human being, it may probably be put clown to the Cuckoo 

 herself ; but I confine myself to the facts as I saw them. Another 

 nest was destroyed in my absence. The young in the remaining 

 one had flown by July 8th, and I heard singing again on the 

 9th (<?/. ' Zoologist,' 1898, pp. 356-8). 



1899, May 31st. — Birds singing in usual place, but faintly, as 

 if just arrived. A nest had been begun on June 18th. The young 

 had flown by July 6th, when I returned after absence from home. 

 There were probably one or two more nests. 



1900, May 30th.— Bird singing well in the usual place. The 

 osier-bed was in a very wild and overgrown condition, and hardly 

 so well suited to the birds as it had been the last year or two. 

 They seem always to prefer to build near the edge, and in spots 

 where the growth is not too dense and heavy. Still, on June 

 14th two nests were being built, one in osiers, the other in 

 meadow-sweet. On the 24th the one in osiers contained five 

 eggs ; the other had two eggs, which resembled those of a Eeed- 

 Warbler. The latter is a very rare bird in this district, common 

 as it is in the upper Thames Valley not far away ; and, as the 

 eggs of the two species do occasionally approximate in colouring, 

 it is just possible that this was really a Marsh-Warbler's nest, as 

 I had judged by its structure. But it was forsaken shortly after 

 this, and I was unable to determine the point. In a third nest an 



2i2 



