595 
marked, yet tlie brown not the mottled brown of a Thrush. A 
cock IJlackbird will occasionally retain large patches of the brown 
ot immaturity to the spring following its birth, when it would be 
about a year old, as some young Kooks retain their nasal bristles a 
twelvemonth or more. A Klackbird in this state might at first 
sight be supposed to be a hybrid. Many continental collections in 
countries Avhere the chasse aux fjrives is largely carried on, as 
at hcrlin, Tuiin, and IMarseilles, have most curious varieties of 
Uio Thrush tribe, including, possibly, some hybrids. The subject 
is interesting, owing to the dissimilarity of the two birds ; though, 
indeed, they are not more dissimilar than the Greenfinch and the 
lamipt. Jh-obably among closely-allied species there are far more 
hybrids than we are aware of.” There are, however, several 
suppositions by which wo may account for some, at least, of the 
foregoing instances, without necessarily supposing them to be cases 
ot interbreeding, lor example, two diflerent species of bird have 
before now not unfrequently been known to lay in the same nest ; 
and there can, I think, be no manner of doubt that Xo. XIl. is a case 
in point; while, possibly, Xos. If. and IX. belong to this class. 
Then there are many people, not intimately acquainted with birds, 
who are unaware that the female Klackbird is not of the deep 
black ot the male, but of a dark brown, and spotted on the breast 
and Uiroat. The young, too, are striped and spotted all over with 
leddish-brown, and, like the female, might easily bo mistaken for 
the Thrush by ignorant persons ; indeed, it is possible that this lias 
been the case in 2s os. I\ ., X., and VIII., and, perhaps, V. The Klack- 
bird and the Thrush both use mud in the construction of their nests, 
but different individuals do so to a very different extent. If the 
former were, on any occasion, to employ more mud than usual, or 
the latter to useless, error might thus arise, judging only from the 
nest ; and, perhaps, Xos. III., VII., and XVIII. are cases of this. As 
those gentlemen I have quoted, wlio speak of the variability of 
Klackbirds’ eggs, bring forward nothing to prove that such eggs are 
not the result of a hybrid union, we may as well take the benefit of 
the doubt, and say that it is at least possible that they were so, 
although the absence, so for as I know at present, of adult 
birds presenting unmistakable marks of hybridism certainly 
opposes this view. Setting aside, however, all doubtful cases, there 
still remain several which, although not sufficient thoroughly 
