808 Linneean Society. 



published in the Phil. Trans, for 1832) from the anatomical examina- 

 tion of specimens in England*. 



A communication from Professor Buckland was read, " On the 

 adaptation of the structure of the Sloth to its peculiar mode of life." 



The opinion of mankind in general, as well as of all naturalists to 

 the present time, has been, that the sloths are instances of imperfect 

 organization. Differing in many respects in their plan of structure 

 from other quadrupeds, every difference was considered to be a de- 

 fect j and hence they were supposed to be condemned to lead a life 

 of misery. Cuvier remarks, that the elephant alone varies in as great 

 a degree as the sloth, from the general plan of nature in the formation 

 of this class ; but the variations in the elephant correspond with one 

 another, so as to produce a harmonious result adapted to its habits, 

 " mais dans le paresseux chaque singularity d'organization semb!e 

 n'avoirpour resultat que la faiblesse et l'imperfection, et les incom- 

 modites quelle apporte k l'animal ne sont compensees pas aucune 

 avantage." (Ossemens Fossiles, vol. v. part 1. p. 73.) 



These notions have arisen from a want of attention to the habits of 

 the animal, which are described by Professor Buckland, from the in- 

 formation of Mr. Burchell, and by quotations from the works of Piso 

 and Marcgrave, and Mr. Waterton. 



The sloths spend their whole lives in trees j and the forests of Brazil, 

 and other parts of South America where they are found, are generally 

 so dense, that they can move from tree to tree by the interwoven 

 branches without descending. When obliged to come down, their 

 passage on the ground, to reach the next nearest tree, is attended 

 with much difficulty, as they are not formed for walking. Their food 

 consists of the young leaves and buds ; and these furnish them with 

 sufficient moisture, for (as Mr. Burchell observed in the case of several 

 which he kept) they never drink. 



They climb trees with ease, and hang to the branches by their long 

 and curved claws. In this position suspended with their back down- 

 wards, they move along under the branch with facility, and sufficient 

 rapidity to surprise those who have observed only their awkward 

 attempts at progression on the ground. They generally sleep in the 

 fork of a branch, with all their four legs clasped round it. 



Professor Buckland examines in detail the anatomical structure of 

 these animals, and quotes the accounts given by authors who have 

 written upon them ; from which it is shown, that so far from the pe- 

 culiarities of their form and organization being sources of inconve- 

 nience and instances of imperfection, they are beautiful adaptations 

 to their peculiar habits. 



The position of the feet, and the form and size of the claws, are 

 admirably suited for grasping a branch ; and the length of the arm 

 and fore-arm enables them to reach the end of the branches which 

 are too slight to bear their weight. 



It has long been observed, that the sloth differed from all the other 

 mnmmalia in the number of the vertebras of the neck, which is nine, 



* A notice of Mr. Owen's paper will be found in Lond. & Edinb. Phil. 

 Mug. & Journal, vol. i. p. 384. — Edit. 



