450 DR. p. CHALMERS MITCHELL ON LONGEVITY AND 



No. of Av. dur. Max. dur. 

 Indiv. in mouths, in iiiouths. 



Sphingu7~us insidiosi.cs (Guianan Tree 1 40 40 



Porcupine). 

 S. mexicanus (Mexican Tree Por- 17 7 



cupine), 

 aS*. prehensilis (Brazilian Tree Por- 9 15 47 



cupine. 

 S. spinosus (Spiny Tree Porcupine) .1 1 1 



S. villosus (Hairy „ „ ) . 6 40 107 



The Porcupines are another set of animals regarding the lon- 

 gevity of which I am unaware of published information, and it is 

 most interesting to find that they attain considerable ages, the 

 record of over twenty years for a common porcupine being re- 

 markable for. a relatively small vegetable-feeding animal. The 

 high average duration (over 7 years) of the whole genus Hystrix 

 shows that these animals have a high viability. The contrast 

 between the records of maximum and average durations for the 

 genus Hystrix and those for other genera is extremely interesting. 

 In the period in question, the species of Hystrix have been given 

 free access to the open air and unheated shelters, whilst examples 

 of other genera have been for the most part kept inside artificially 

 heated houses. 



Oapt. Stanley Flower's record cases ai-e not so high. 



p, T a? -^°- ^^ ^^'- ^^'^- Max. dur. 



UHINCHILLID^. Indiv. in montlis. in months. 



Chinchilla lanigera {QhinchWXfi) 38 30 84 



Lagotis cuvieri (Cuvier's Lagotis) ... 1 18 18 



Lagostomus trichodactylus (Viscacha) 30 32 81 



DASYPROCTIDiE. 



Ccefo^gwys j9«c« (Spotted Oavy) 35 22 92 



Dasyjjrocta, whole genus lUl 31 109 



D. acouchy (Acouchy) 4 33"5 61 



D.aguti (Golden Agouti) 20 27-7 101 



D.azarce (Azara's „ ) 3 94 109 



D. cristata (West Indian Agouti) 29 27 99 



D.isthmica (Central American ,, ) 15 31 97 



D. mexicana (Mexican ,, ) 2 11-5 14 



D.prymnolopha{Ka.\Yj-T\xm\)edi ,, ) 20 32 108 



D. punctata (Punctated ,, ) 8 28 84 



Oaviid^. 

 Dolichotis patachonica (Patagonian 18 30 93 



Oavy). 

 Cavia flavidens (Yellow-toothed 1 10 10 



Cavy). 



C. spixi {Spix's Giivy) '.. 4 28 48 



Cerodo7i 7'topestris (Rock-CsiYj) 4 14 40 



Hydrochoerus capyhara (Capybara) ... 18 33 114 



