LONGEVITY AND RELATIVE VIABILITY IN MAMMALS AND EIllDS. 425 



24. On Longevity and Relative Viability in Mammals and 

 Birds ; with a Note on the Theory of Longevity. By 

 P. Chalmers Mitchell, M.A., D.Sc, LL.D., F.R.iS., 



Secretary to the Zoological Society of London. 



[Received February 6, 1911 : Read March 7, 1911.] 



Contents. 



Introduction 



Mammalia (8110 examples)... 

 Quadrumana (3084 „ )... 



Summary of Quadrumana 



Carnivora (1741 examples)... 



Summary of Carnivora 



Insectivora ( 67 examples)... 

 Chiroptera (92 „ )... 

 Rodentia (1330 „ )... 



Summarj' of Rodentia 



Hyraces ( 12 examples)... 

 Proboscidea ( 4 „ )... 

 Ungulata (1035 „ )... 



Perissodactyla (46 „ ) . . . 



Suramar}' of Perissodactyla ... 



Artiodactjda (989 examples)... 



Summary of Artiodactyla 



Cetacea & Sirenia 



Edentata (123 examples) 



Summary of Edentata 



Marsupialia (618 examples) ... 



Summary of Marsupialia 



Monotremata (4 examples) 



Summarj' of Mammalia 



Aves (12,977 examples) ... 



Passeres( 3224 „ ) 



Summary of Passeres 



Picariai (455 examples) 



Summai-y of Picarise 



Striges (432 examples) 



Summary of Striges 



Psittaci (1479 examples) 



Summary of Psittaci 



Accipitres (893 examples) 



Summary of Accipitres 



p. 425. 

 p. 429. 

 p. 429. 

 p. 435. 

 p. 436. 

 p. 443. 



444. 



444. 



445. 



451. 



452. 



452. 



453. 



453. 



454. 



454. 



461. 

 p. 462. 

 p. 462. 



463. 



464. 



467. 



467. 



467. 



470. 

 p. 470. 

 p. 485. 

 p. 487. 

 p. 491. 

 p. 492. 

 p. 493. 

 p. 494. 

 p. 500. 

 p. 501. 

 p. 505. 



Steganopodes (165 examples)... 



Summary of Steganopodes 



Herodiones (480 examples) 



Summary of Herodiones 



Odontoglossffi (23 examples) ... 



Palamedeffi (22 examples) 



Anseres (1545 examples) 



Summ ary of A nseres 



Columbai (932 examples) 



Summary of Columbas 



Pterocletes (83 examples) 



Gallinse (1660 examples) 



Summary of Galling 



Hemipodii (15 examples) 



Fulicarise (214 examples) 



Summary of Fulicariffi 



Alectorides (221 examples) 



Summary of Alectorides 



Limicolas (393 examples) 



Summary of Limicolse 



Gavise (241 examples) 



Summarj' of Gavise 



Tubinares (10 examples) 



Pygopodes (86 examples) 



Impennes (62 examples) 



Crypturi (146 examples) 



Apteryges ^22 examples) 



Casuarii (77 examples) 



Strutliiones (97 examples) 



Summary of Aves 



General Summary and Con- 

 clusions 



Note on the Theory of 

 Longevity 



p. 506. 

 p. 507. 

 p. 508. 

 p. 510. 

 p. 511. 

 p. 511. 

 p. 512. 



515. 



516. 



519. 



519. 



520. 

 p. 523. 

 p. 524. 

 p. 525. 

 p. 526. 

 p. 526. 

 p. 528. 

 p. 529. 

 p. 530. 

 p. 530. 

 p. 531. 



53L 



532. 



532. 



533. 



533. 



534. 



535. 



535. 



p. 540. 

 p. 545. 



Introduction. 



Animals are mortal, and we know that death comes to them 

 after durations of life that differ much in different individuals 

 and species. Unfortunately, except in the rarest cases, it is 

 impossible to obtain information as to the duration of life in wild 

 animals. Enquiry into the frequency of death in domesticated 



