RELATIVE VIABILITY IN MAMMALS AND BIRDS. 449 



close. As in proportion to their size these rodents have rather a 

 high viability, it must be supposed tliat the conditions of detention 

 in the interior of a house are not very unfavourable to them. 



„ No. of Av. dur. Max. dur. 



toPALACID^. Indiv. in months, in months. 



Rhizomys badius (Bay Bamboo-Rat) .5 17-4 41 



DlPODID^. 



JDipus cegyptiiis CEgjptinn J erhot\) ... 48 18'8 56 



D. hirtipes (Hairy-footed Jerboa) ... 30 16 36 



DipocUUus swioni (Simon's Dwarf 3 20 23 



Jerboa). 



D. campestris (Dwarf Jerboa) 1 12 12 



Alactag a indica {InAi&n 3 evho^) 1 14 14 



A . decumana (Persian Jerboa) 2 10"5 13 



If Jerboas can be compared with rats and mice, the record of 

 nearly five years for an Egyptian Jerboa is what might be ex- 

 pected, but the maxima for most of the species and the average 

 durations show a low viability. The Jerboas have always been 

 kept in a warmed house. 



rv^,^,.,-vT^r^^.TmTT^ !c No. of Av. duv. Max. dur. 



(JCTODONTIDJi;. T ,• • ., • ,, 



Indiv. in months. m montiis. 



OciocZoH c^M?^m(7^ (Cuming's Octodon) . 35 24 62 



Ctenodactylus gundi (Qvindii 'Ka.t) ... 2 5*5 7 



Myopotamus coypu (Coypii) 39 30 121 



Capromys hrachyuncs (Short-tailed 3 11 15 



Capromys). 



C. jOiYoHfZes (Fournier's Capromys) ... 5 36 116 



Aidacodus sivindey-nianus (Ground- 2 10 '5 16 



Rat). 



Some of the Octodontidfe are relatively large rodents and the 

 record of 10 years for a Coypu is not surprising. The viability 

 as shewn by the average duration is not high ; in the case of the 

 Coypus, which have always been provided with access to the open 

 air, the average duration is lowered by high mortality amongst 

 young born in the Gardens. 



HySTRICID^. ^°-o* a v. dm-. Max. dur. 



Indiv. in months, in months. 



^2/sfH.ij, whole genus 34 89 245 



H.cristata (Crested Porcupine) ... 26 70*9 245 



H. javanica (Javan ,, )•■■ 6 123 181 



H.longicauda {^MYaa^ivnn „ ) ••• 2 137 163 



Atherttra africana (African Brush- 8 26*3 117 



tailed Porcupine). ^ 



7l./«sacwZ« to (Indian Brush-tailed ,, ). 2 29 * 50 



JErithizon dorsaius (Canadian Por- 3 18*3 32 



cupine). 



S'2Jhingurus, whole genus. 18 23 107 



