260 ._ THE ZOOLOGIST. 
May the desired opportunity was afforded for examination. Both birds 
were males, by dissection, and neither of them had any trace of the knobs 
on the bill, the surface of the upper mandible being quite level along its 
ridge. On April 25th I examined a live Norfolk Plover, which was 
supposed to be a male, and it also had no knobs on the bill, but this is not 
conclusive, for the sex was not definitely ascertained. On the other hand, 
a knob—as large as in the plate referred to—was distinctly visible in 
a male which was unfortunately shot near Holt, in Norfolk, on or about 
the 20th of May last, and was discernible seven days after the bird was 
stuffed. I was told by Mr. Dack, who mounted it; that when fresh the 
knob was rounded, but that in a week’s time it had become shrivelled, 
though still quite apparent. This bird, however, had ouly one knob on the 
bill, not two as in Mr. Booth’s figure, though in the same position, viz., on 
the ridge of the upper mandible and almost at its base.—J. H. Gurney, Jun. 
(Keswick, Norwich). 
Hybrid Waterfowl.—In the Newcastle Museum there may be seen the 
skeleton of a hybrid Swan bred between a female Whooper, Cygnus ferus, 
and a male Mute Swan, C. olor. In this hybrid, which was reared on 
Gosforth Lake, in Northumberland, the trachea does not enter the sternum, 
which nevertheless is slightly hollowed as if to receive it. A year or two 
ago I was shown in London a supposed hybrid between a Black Swan and 
a Mute Swan, and a similar hybrid was once reared in County Cork (Proc. 
Zool. Soc. 1847, p. 97). A hybrid between a Wild Swan and a Goose has 
been described (Ann. Mag. Nat. Hist. xii. p. 119), but it is doubtful if it was 
such. My father has a hybrid between an Egyptian Goose and a domestic 
Duck of the Penguin breed. No birds are more liable to hybridism than 
Ducks, especially in confinement, and no two kinds interbreed more readily 
than the Pintail (Anas acuta) and Mallard (A. boschas). I have had two 
examples of this cross, and many years ago I believe my father had several of 
them alive, though unfortunately none of them are now in existence. A 
rare cross is that between Wild Duck and Sheldrake: of this cross a duck 
and drake, as we are informed in Hele’s ‘ Notes about Aldeburgh,’ were 
killed near that place in January, 1864, and it was suggested by a 
writer in ‘The Field,’ that as this cross had been successfully bred at 
Saxmundham, the pair may have escaped from there. The only other 
instances known to me are a drake obtained at Cambridge by Mr. Whitaker, 
and given by him to Mr. William Borrer, and a brood which, according to 
Messrs. Harvie-Brown and Buckley (‘ Fauna of the Outer Hebrides,’ p.102), 
were bred in North Uist.—J. H. Gurney, Jun. (Keswick, Norwich). 
Habits of the Cuckoo.—A pair of Cuckoos have this year chosen a 
position for their spring operations in my garden well suited for observa- 
tion. The nest is a Hedgesparrow’s, in a bush near a pigsty. There 
