110 Darwin and Romanes dealt with. 



are laid ; that its young are hatched simultaneously. 

 But if it is right to trace the origin of the European 

 cuckoo's instinct in the nesting habits of the American 

 coccyzus, it might be attributed, not to the aberrant 

 habit of perhaps a single species, but to another more 

 disadvantageous habit common to the entire genus — 

 their habit of building exceedingly frail platform 

 nests, from which the eggs and young very frequently 

 fall." * 



Major Bendire's remark about simultai(J^ty of young 

 hatched — if we admit the correctness of his observa- 

 tion — is not conclusive against our position, nor does 

 it really touch it. What we hold is, that absolute 

 simultaneity does not exist in any strict sense ; that 

 in any case there is only the more or less close ap- 

 proach to it. Eggs vary in size, in thickness of shell, 

 etc., just as much as to provide the margin we claim. 

 Besides, Major Bendire here founds, not on one of 

 the more common species, but on one which he does 

 not even treat of — at all events, under this name — in 

 his Smithsonian volume, where he distinctly says of 

 the yellow-billed cuckoo, that as to incubation there 

 is no absolute rule. Sometimes it does not begin till 

 laying is done, and in other cases incubation is begun 

 when the first egg is laid.f But the Major's argu- 

 ment against Darwin is conclusive. 



Further still, with regard to intervals between the 

 laying of eggs, there is in no species whatever the 

 uniformity which Mr. Darwin seems to found on here. 

 Sudden frost and cold will completely stop egg laying. 

 Once in the case of starlings, which I could observe 



* Sniithson Report, 1893, p. 610. 

 tP- 23. 



