RELATIVE VIABILTTY IN MAMMALS AND BIRDS. 437 



No. of 

 Indiv. 



Felis cafm (K.M,fFer Cat) 3 



F. maniculata (Fettered Cfit) 2 



F. yaguarundi (Yaguarundi Cat). . . 5 



F. eyra (Eyra Cat) 10 



F. 2xirdcdis (Ocelot) 56 



F. tiyrina (Tigrine Cat) 4 



F. geo^roii (Geoffroy's Cat) 10 



F. passerum (Pampas Cat) 2 



The records of avei-age and maximum duration of these smaller 

 Oats are very irregular, and in many cases the numbei'S are too 

 small for the result to be more than accidental. We do not know 

 what is the potential longevity of the smaller cats ; it may be 

 expected to be less than that of large cats, and has been estimated 

 at something over twenty yenrs. It is clear that the difference 

 between average dui'ation and potential duration has been much 

 greater in the case of the small cats than in that of the large 

 cats. The domestic cat is notoriously a hardy animal, and I 

 should hesitate to infer a lower viabiUty for small cats than for 

 large cats. In the first place, throughout the period under dis- 

 cussion, the majority of the large cats were kept in the Lion House, 

 a building in which the ventilation and bulk of air per inhabitant 

 were fairly good, whilst, although there was not free communi- 

 cation with the outer air, there were outdoor cages, to which on 

 occasion the animals had access. The smaller cats, on the other 

 hand, were kept in a smaller and darker house, with much less 

 ventilation, more heating, and no access to the open air. In the 

 second place, there is an important natural difference with regard 

 to feeding, which has not been allowed for systematically. The 

 larger cats are accustomed to make an occasional kill, and to 

 return to a carcase even after it is putrid. The smaller cats, on 

 the other hand, devour tl';eir smaller prey as soon as they have 

 killed it, and unless under the pressure of serious hunger, take 

 nothing except quite fresh food. In accordance with their natural 

 habits, the larger cats are little injured by food which is not quite 

 fresh, whilst the smaller forms are highly susceptible to intestinal 

 ailments arising from the quality of their food. I am convinced 

 that the necessity for extreme care in the qTiality of food given to 

 the smallei" cats has not been sufHciently realized. 



I do not think there can be any doubt, however, that both with 

 smaller and larger Felidae, the necessity of access to the open air, 

 at the choice of the animals, has not been appreciated, and that 

 the low viability under menagerie conditions is due to this neglect. 

 Most of them are partly nocturnal, many of them cover a wide 

 climatic range, and as in many, if not all furred animals, the 

 thickness and length of their coat increase rapidly with exposure 

 to low temperatures. No doubt provision for basking in the 

 .sun, or for warming themselves in aitificially-heated retreats, is 



Piioo. ZooL. See. —1911, No. XXIX. 29 



