for the favoured one. J for one must lead myself on to the debatable ground, and say that the vigilant eye of the parent Cuckoo, in my opinion, must have led her to clear out the impediments to the proper care of her progeny. It being concluded that the Cuckoo about the time which she deposits an egg in a nest habitually does extract an egg of the bird's, but not always, we may reason that she may more or less habitually clear out the latter's offspring. Failing in the latter, the young Cuckoo can do so for itself in due course. Whether dead young birds would be carried away by her is more doubtful; probably, as in some cases at least where the young one expels, the foster-birds clear away.—Wm. Wilson (Alford, Aberdeen).
Date of Arrival of the House Martin.—I am glad that Mr. Warde Fowler has called attention (ante, p. 267) to the apparent alteration in the date of arrival of the House Martin (Chelidon urbica), as it has much puzzled me to account for its having been so late in its spring appearance in South Devon since 1891. Previous to that year I had always seen the first House Martin in April, and in the year before that (1890) as early as the 9th of that month. Since then I have never observed it before May, except in 1894, when April 20th was the date of its arrival at Exmouth. Although in 1891 I did not see any in Exeter till May 14th (when there were a few only to be seen), it was observed at Swanage, in Dorset, on April 11th, and at Kingsbridge, in South Devon, on April 24th. Again, in 1897 I did not notice any at Chagford, Devon, till May 3rd; but House Martins had been seen by the Rev. Murray A. Mathew at Buckland Dinham, Somerset, on April 6th. This year I saw none till June 19th at Topsham, and at Chagford, at the end of the month, there were very few in the streets, though it is usually a very abundant species there. One, however, was seen by Mr. Mathew at Buckland Dinham on April 26th, and it appears to have been as numerous as usual there. In this neighbourhood it has been very scarce all the summer. It would appear from the late Mr. T.R. Archer Briggs's notes that the House Martin is always later in arriving in the Plymouth district than about Exeter, and the late Mr. J. Gatcombe observed some arriving with a northerly wind on May 3rd, 1873, although near Topsham it arrived in large numbers from the south on April 16th. In 'The Zoologist' for 1845, pp. 1189 and 1890, are some observations on the arrival of spring migrants at Devonport by W. Harris Bow, who gives the following dates of arrival for the House Martin: — 1841, May 3rd; 1842, May 9th; 1844, May 2nd; 1845, May 5th. In 1895 I observed House Martins at Bovey Tracey, Devon, on May 1st; and when Mr. Mathew and myself were at Slapton Ley, on the south coast, on May 9th, House Martins were in great numbers perched on the
