462 DR. p. CHALMERS MITCHELL ON LONGEVITY AND 



CETACEA AND SIRENIA. 



Very few examples are contained in tlie records, and the 

 duration of these was only sutiicient to show the complete 

 unsuitability of the conditions and certainly alforded no indication 

 as to the general viability and longevity of these animals. There 

 is of course abundant evidence from other sources as to the high 

 potential longevity of Cetaceans, but I know of no definite 

 evidence with regard to Sirenians, which as vegetable-feeders 

 with complicated intestines might be supposed to have short lives 

 in proportion to their bulk. 



EDENTATA. 



Tj . ■„ ^ ^ ^ ^ No. of Av. dur. Max. dur. 



Bradypodid^. 1,^^;^_ i,^ „^„„^i,^_ -^ ,^^^„ti„_ 



BradypiijS tridactylus (Three-toed Slotli). 8 underl 1 



Cholopus didaciylus i^vfo-toedi '^\ot\\) ... 2 7 13 



C. hoffmanni (Hoffmann's Sloth) 14 29 133 



I am ignorant as to any recorded information regarding the 

 potential longevity and viability of Sloths. Lydekker, in the 

 Royal ISTatural History, remarks on their power of I'ecovery from 

 injury and capacity for enduring long periods of starvation, 

 correlating these qualities with general low organization, and 

 comparing the animals with reptiles. Certainly, however, it 

 cannot be assumed that creatures of low organization have a 

 relatively high potential longevity. As Sloths are rather small, 

 vegetable - feeding animals, with fairly bulky hind-guts, on 

 Metchnikofi's theory, their duration of life and viability ought 

 to be low. The maximum record of over 11 years for a 

 Hoffmann's Sloth is certainly high, but the average dux^ation of 

 Sloths is extremely bad. The failure has been complete in the 

 case of the Three-toed Sloths, very great with the Two-toed, 

 whilst there has been a partial but very irregular success in the 

 case of Hoffmann's Sloth. Sloths are nocturnal inhabitants of 

 tropical forests, and in captivity they have been assigned confined 

 quarters in warmed houses, without access to the open air. 

 Their quiescence by day probably has led to the need of air and 

 exercise at night being overlooked. 



DaSYPODIDJI:. ^"-f .A^'-d"v. Max. dm-. 



liidiv. ni months, iii uioiitlis. 



Tafifsw A;^&HcZc« (Mulito Armadillo) ... 6 8'5 40 



7'. jijeSa (Peba Armadillo) 16 17 45 



:Z'. ^fl;P/>Ze?'i (Kappler's Armadillo) _ 2 53 54 



i)as2/pts «^^5i^^i^^s (Little Armadillo) ... 6 19 23 



Z>. setccMiciits (Six-banded Armadillo) ... 6 9*3 19 



Z). m'ZZostis (Hairy Armadillo) 31 33 157 



Xenicrus unicinchis (Broad-banded 2 6 11 



Armadillo). 



Tolypeides tricinctus (Brazilian Three- 18 8 

 banded Armadillo). 



