24 Mr. J. H. Gurney — Comparative 



Bubo maximus, about 35 clays [Gurney). 

 Aquila, 30-35 days [Evans). 



Sarcorhamphus, 54 days [Broderip). 



Anser dumesticus, 30 days [Evans). 

 Cygnus olor, 36 days [Stevenson). 



So far as tliey go these support the theory, but unfortu- 

 nately there are also many exceptions to invalidate it. To 

 take only one : a domesticated Wild Duck requires 28 

 days to hatch her eggs, and the domesticated Muscovy Duck 

 37 days ; but one lives as long as the other so far as we know, 

 though poultry-keepers do not commonly give any Ducks the 

 chance of very great longevity^. 



It is abundantly proved that so long as health remains to 

 them the majority of birds can go on breeding, as Mr. Meade- 

 Waldo's Eagle-Owls, to be mentioned presently, testify. It 

 is so with the domestic Goose of our farmyards. Mr. L. 

 Wright says : — " The Goose lives, lays, and produces strong 

 and healthy progeny to a very advanced age, many cases 

 being recorded of birds being in full breeding to at least 

 forty years old." [' The Book of Poultry/ p. 560). What is 

 true of Anser domesticus and Bubo niaxinius is also true of 

 many other birds. Their vocal powers are likewise known to 

 remain strong and vigorous for a very long period : a Black- 

 bird of 20 continued to sing well [' The Belfast Commercial 

 Chronicle,' Dec. 25th, 1839) and a Skylark nearly as long 

 ('Zoologist,' 1865, p. 9604), while a Gymnorhina tibicen of 

 26 was noisy to the last. If birds can sing as long as that 

 in a cage, there is probably no limit in a wild state. Johann 

 Naumann instances a Cuckoo which called, season after 



* It is generally held hj tbose best qualified to judge (though not by 

 Prof. Newton) that there is also some correspondence between age and 

 gestation in mammals, at any rate in the larger Mammalia. The subject 

 has lately been revived and ventilated in ' The Field ' newspaper (see 

 February 5th and 12th, 1898), and some facts and some theories put 

 forward about elephants by Col. Pollock and Mr. Cameron. The idea 

 is as old as Pliny, commenting on whom Willughby and Ray remark : 

 " If Animals of different kinds be compared together, as for example 

 Birds with Beasts, those will sometimes be found to be most vivacious 

 [long-lived] which are borne the least while in the womb." 



