538 Zoological Society. 



June 11. — " On the Blood-corpuscles of the Two-toed Sloth, Bra- 

 dypxis didactylus, Linn.," by George Gulliver, F.R.S. 



From an observation which I have lately made, it results that the 

 Two-toed Sloth is one of the very few animals that has blood-discs 

 considerably larger than those of Man. 



The following measurements of the blood-discs of the Sloth are 

 given in vulgar fractions of an English inch : — 



1-3200"] 



1-3000 



1-2888 



1-2823 )>Common sizes. 



1-2769 



1-2664 



1-2583^ 



1-42661 Tj . 

 1-2286 r^^*''^""^'- 



1-2865 Average. 



M. Mandl* discovered that the blood-corpuscles of the Elephant 

 are the largest at present known belonging to the Mammalia, and I 

 subsequently found that those of the Capybara were, as far as we 

 then knew, next in size, as noticed in my Appendix to Gerber's 

 Anatomy, pages 5, 8, and 50. 



But it now appears that the blood-corpuscles of the Sloth are 

 larger than those of the Capybara, and, among mammiferous animals, 

 second only in magnitude to the corpuscles of the Elephant. 



For the sake of comparison, some of my measurements of the 

 average size of the largest blocd-discs of Mammalia are here set 

 down in the order of the magnitude of the discs, and in vulgar frac- 

 tions of an English inch. 



Elephas Indicus, Cuv 1-2745 



Bradypus didactylus, Linn 1-2865 



Baleena Boops, Auct 1-3099 



Hydrocharus Capybara, Erxl 1-3216 



Phoca vitulina, Linn 1-3281 



Dasypus villosus, Desm 1-3315 



Myopotamus Coypus, Desm 1-3355 



Pithecus Satyrus, GeofF 1-3383 



Dasypus sex-cinctus, Auct 1-3457 



Numerous other measurements are appended to the English ver- 

 sion of Gerber's Anatomy. 



It has been said that the blood-corpuscles are larger in omnivorous 

 than in herbivorous and carnivorous animals. To the facts which I 

 have elsewhere t shown to be at variance with this opinion, it may be 



* Anatomie Microscopique, Paris 1838, Prem. Liv. p. 17. M. Mandl's 

 observation refers to the blood-corpuscles of the African elephant j it was 

 those of the Asiatic species that I examined. 



f Appendix to Gerber's Anatomy, p. 4-5, 



