312 THROUGH THE HEART OF PATAGONIA 



consideration thus resembles that of the sculptured tubercles of Mylodon 

 in all essential features, but differs in two noteworthy respects. In the 

 ossicles of the so-called Neomylodon, as already described, the fibres of 

 connective tissue do not exhibit much definite radiation towards the lateral 

 margin ; while the bony tissue at most points is disposed in definite 

 Haversian systems. There is thus enough discrepancy to justify the 

 suspicion that the new and the old specimens do not belong to the same 

 animal. In fact, so far as the differentiation of the dermal bone is con- 

 cerned, the so-called Neomylodon is precisely intermediate between Mylodon 

 and the existing Armadillo {Dasypus) ; sections of the scutes of the latter 

 animal, both in the Royal College of Surgeons and in the British Museum, 

 showing that in this genus nearly the whole of the osseous tissue is 

 arranged in Haversian systems, although abundant interlacing connective- 

 tissue fibres are still entangled in it, at least near the border 



If the characteristic dermal armature does not suffice for the definite 

 expression of an opinion as to the precise affinities of the specimen, a still 

 less satisfactory result can be expected from a comparison of the hair. 

 For, in the first place, no hair has hitherto been discovered in association 

 with the skeleton of any extinct Ground-Sloth. ; while,- secondly, the hairy 

 covering of a mammal is perhaps that part of its organisation most readily 

 adapted to the immediate circumstances of its life. So far as their endo- 

 skeleton is concerned, the extinct Mylodonts and their allies are precisely 

 intermediate between the existing Sloths and Anteaters ; they combine 

 " the head and dentition of the former with the structure of the vertebral 

 column, limbs, and tail of the latter."* It might therefore be supposed 

 that the hair of this extinct group would exhibit some of the peculiarities 

 of that in one or other of its nearest surviving relatives. The epidermal 

 covering of the piece of skin now described, however, entirely lacks the 

 under-fur which is so thick in the Sloths ; while the structure of each 

 individual hair, with its smooth cuticle and lack of a medulla, is strikingly 

 different from that observed both in the Sloths and Anteaters, and identical 

 with that of the hair in the surviving Armadillos. The large hair in the 

 Sloths and Tamandua exhibits a conspicuously scaly cuticle ; while that 

 of Myrmecophaga is remarkable for its very large medulla. All these 

 animals now live in the tropics, either in forests or swamps, whereas the 

 Patagonian animal must have existed under circumstances much like 

 those under which the Armadillos still survive. Hence the characters 

 of the hair of the so-called Neomylodon may be of no great importance in 

 determining the affinities of the animal, but may represent a special 

 adaptation to its immediate environment. 



Finally, there is the question of the antiquity of the problematical 

 skin. On two occasions I have examined the mummified remains of the 

 - Flower and Lydekker, " Introduction to the Study of Mammals," p. 183. 



