184 Mr. G. D. Rowley on certain Facts in 



the idea), that the Cuckoo's eggs, whicli differ in colour and 

 marking from those of the owners of the nest in which they are 

 found, are normal, while his specimens are accidental — in short, 

 exactly the contrary to what he advances. Some of the figures 

 which he gives in his plate (' Naumannia,' 1854, p. 415), I take 

 to be simply monstrous eggs of the several birds in whose nests 

 they were discovered. The author justly remarks that numbers 

 prove a rule, and takes his stand upon his hundred specimens. 

 I cannot now produce quite so many, but perhaps could nearly 

 equal him in the number taken by our respective hands in situ. 



Dr. Baldamus admits that the two types of coloration in the 

 eggs of the Cuckoo, which are known to all oologists, namely 

 the red type and the grey, are found in most localities ; and, with 

 some slight variation (induced, perhaps, by exhaustion or other 

 similar physical causes), I cannot imagine any other sort of colo- 

 ration. But if such polymorphism be found in eggs of the Cuckoo, 

 they can scarcely surpass in variety the eggs of Anthus arboreus. 

 For what purpose then, I may ask, was this most extraordinary 

 variability given to the Tree-Pipit, which is certainly not a parasi- 

 tical species? 



The author concludes his most interesting and clever paper 

 by laying down fourteen Canons, which I here repeat, adding to 

 each my own comment upon it. 



1. "The Cuckoo deposits its eggs for incubation with a great 

 number of Warblers." — True. 



2. " There are Cuckoos' eggs of such different coloration 

 and marking, as are found in no other bird, so far as is 

 known up to this time." — To this I do not agree. 



3. "All the eggs of the Cuckoo, even those of the most 

 varied colouring, find a resemblance, alike in coloration 

 and marking, among those of the foster-parents." — I do 

 not agree. 



4. " Peculiar colouring prevails in different localities." — True. 



5. "Each hen Cuckoo deposits only one egg in the same 

 nest." — True. 



6. " Eggs (as a rule) are deposited only in such nests as already 

 contain eggs of the foster-parents." — Usually the case, but 

 by no means always, as I believe. 



