64. 



and the vast mass of nervous fibre from which those muscles derived 

 their energy. The natural co-adaptation of the articular surfaces 

 shows that the ordinary inflection of the end of the tail was back- 

 wards as in a caudafulciens, not forwards as in a cauda prehensilis. 

 Dr. Lund's hypothesis, therefore, that the Megatherium was a 

 climber and had a prehensile tail, is destroyed by the now known 

 structure of that part. 



But viewing, as the author conceives, the pelvis of the Mega- 

 therium as being the fixed centre towards which the fore-legs and 

 fore-part of the body were drawn in the gigantic leaf-eater's efforts 

 to uprend the tree that bore its sustenance, the colossal proportions of 

 its hind extremities and tail lose all their anomaly, and appear in 

 just harmony with the robust claviculate and unguiculate fore-limbs 

 with which they combined their forces in the Herculean labour. 



The author then referred to the Mylodon robustus, a smaller ex- 

 tinct species of the same natural family of phyllophagous Bruta, and 

 to the additional arguments derivable from the skeleton of that 

 animal in favour of the essential affinity of the Megatherium to the 

 Sloths ; and the light which the remarkable healed fractures of the 

 skull of a specimen in the Museum of the College of Surgeons 

 threw upon the habits and mode of life of the species. 



Finally, with reference to the hypothesis of the German authors 

 and artists of the degeneration of the ancient Megatherioids of South 

 America into the modern Sloths, the author remarked that the 

 general results of the labours of the anatomist in the restoration of 

 extinct species, viewed in relation to their existing representatives 

 of the different continents and islands, commonly suggested the idea 

 that the races of animals had deteriorated in point of size. Thus 

 the palraated Megaceros is contrasted with the Fallow-deer, and the 

 great Cave-bear with the actual Brown Bear of Europe. The huge 

 Diprotodon and Nototherium afford a similar contrast with the 

 Kangaroos of Australia, and the towering Dinornis and Palapteryx 

 with the small Apteryx of New Zealand. But the comparatively 

 diminutive aboriginal animals of South America, Australia and New 

 Zealand, which are the nearest allies of the gigantic extinct species 

 respectively characteristic of such tracts of dry land, are specifically 

 distinct, and usually by characters so well marked as to require a 

 subgeneric division, and such as no known or conceivable outward 

 influences could have progressively transmuted. Moreover, as in 

 England, for example, our Moles, Water-voles, Weasels, Foxes and 

 Badgers, are of the same species as those that co- existed with the 

 Mammoth, Tichorrine Rhinoceros, Cave Hyaena, Bear, &c. ; so like- 

 wise the remains of small Sloths and Armadillos are found associated 

 with the Megatherium and Glyptodon in South America ; the fossil 

 remains of ordinary Kangaroos and Wombats occur together with 

 those of gigantic herbivorous marsupials; and there is similar evidence 

 that the Apteryx existed with the Dinornis : and the author offered 

 the following suggestions as more applicable to or explanatory of the 

 phenomena than the theory of transmutation and degradation. He 

 observed, that in proportion to the bulk of an animal is the difficulty 



