RELATIVE VIABILITY IN MAMMALS AND BIRDS. 443 



possibly approach the potential longevity of bears, for the con- 

 ditions provided, affording exercise, con.vtant access to fresh air 

 and to shelter, and regular food, must be more natural than in 

 the case of most animals in captivity. The average duration 

 of life of the bears is probably low on account of the number of 

 cubs which are included and which had received unwise treatment 

 as pets. Iv'evertheless, the average longevity is higher than in 

 the case of any other large carnivora, and it is interesting to 

 notice that during the period dealt with these animals, although 

 not given good room for exercise, were freely exposed to the open 

 air, and at the same time provided with some artificial heat. 

 Oapt. Stanley Flower's records are much lower. 



OTARIID.E. ^'';pf .Av.diiv. Max.dur. 



Indiv. Ill months. m months. 



O/.rtT /a, whole genus 6 108 210 



0. californiana (Californian Seadion) .1 51 51 



O. hookeri (Hooker's „ ) . 2 18 34 



O.juhata (Patagonian ,, ). 2 199 210 



O. j':>Msz7^a (Cape Sea-lion) 1 151 151 



Hcdichcei'us gv'yjjhus (Grey Seal) 7 17 73 



Phoca vitulina {fjomvixon ?^Q?i[) 25 20 172 



Monachv.'S albiventer (Mediterranean 2 17 34 



Seal). 



Cystophora cristata (Bladder-nosed 7 4*5 26 



Seal). 



Sea-lions and Seals evidently at least equal in potential longevity 

 other members of the order Carnivora of large size. The relatively 

 low average duration is due to the veiy heavy mortality of young 

 and newly caught animals. The greatest number of deaths are 

 of animals that have lived only a few months in the Gardens ; if 

 they survive that period, and only a small proportion do survive 

 it, their duration of life is very good. They have free access to 

 open air, and no artificial heat. 



Sumtnary of Carnivora. 



Carnivora are generally regarded as animals with relatively long 

 lives and high viability, and the records given above suppoi't such 

 a view. It is curious, moreover, how the maximum durations 

 correspond roughly with the sizes of the animals. Bears reached 

 33 years, Lions and Tigers 17, Sea-lions 17, the smaller Cats 13, 

 "Viverrids 15, Hypenas 13, Jackals 13, Badgers 12, smaller Dogs 

 and Foxes 10, Mustelines 10. On the other hand, comparison of 

 average durations with maximum durations shows in the clearest 

 way that those animals have lived best which have had the readiest 

 access to fresh air, that, in fact, darkness and the bad air of 

 heated houses are much gi'eater dangers to life than cold. 



