3IO THROUGH THE HEART OF PATAGONIA 



lower half of the thickened dermis and the hairs are implanted in every 

 part of its upper half, whereas all the forms of bony armour hitherto 

 described in this order reach the outer surface of the dermis and are 

 merely invested with horny epidermis. This is the case, as is well known, 

 in the common existing Armadillos, in which the hair is only implanted 

 in the dermis between the separate parts of the armour. Even in the 

 unique and remarkable skin of an Armadillo from Northern Brazil, 

 described by Milne-Edwards under the name of Scleropleura bruneti* 

 the bony plates and tubercles are still covered only by epidermis, although 

 most of them are reduced to small nodules and might well have sunk 

 more deeply into the abnormally hairy skin. There is also reason to 

 believe that in the gigantic extinct Armadillos of the family Glyptodontidse 

 the same arrangement of dermal structures prevailed ; for one specimen 

 of Panochthus tuberculatus obtained by Dr. Moreno for the La Plata 

 Museum actually shows the dried horny epidermis in direct contact with 

 the underlying bone, and seems to prove that the numerous perforations 

 in the Glyptodont dermal armour were not for the implantation of hairs 

 (as once supposed), but for the passage of blood-vessels to the base of the 

 epidermal layer. Similarly, among the extinct Ground-Sloths of the 

 family Mylodontidae dermal ossicles have been found with the remains of 

 Ccelodon f and various forms (perhaps different subgenera) of Mylodon ; 

 but the only examples of this armour yet definitely described | exhibit a 

 conspicuously sculptured outer flattened face, and it thus seems clear that 

 Burmeister was correct in describing them as originally reaching the upper 

 surface of the dermis and only covered externally by a thickened epidermis. 

 It is, however, to be noted that Burmeister himself actunlly observed 

 armour of this kind covering only the lumbar region of the trunk. He 

 believed that the other parts of the animal were similarly armoured, because 

 he had found " the same ossicles " on the digits of the manus, where they 

 were "generally smaller and more spherical " ; but he unfortunately omits 

 to make any explicit statement as to the presence or absence of the 

 characteristic external ornamentation on the latter. 



The omission just mentioned is especially unfortunate, because on 

 careful comparison it is evident that the irregular disposition of the small 

 ossicles in the piece of skin now under consideration is most closely 

 paralleled in the dermal armour of the extinct Mylodon, as already 

 observed by Drs. Moreno and Ameghino. There is obviously no approach 

 in this specimen to the definite and symmetrical arrangement of the 



* A. Milne-Edwards, " Note sur une nouvelle Espfece de Tatou k cuirasse incom- 

 plete (Scleropleura bruneti)," Nouv. Arch. Mus. vol. vii. (1871), pp. 177-179, pi. xii. 



f P. W. Lund, K. Dansk. Vidensk. Selsk. Afhandl. vol. viii. (1841), p. '35 (footnote). 



X H. Burmeister, Anales Mus. Publico Buenos Aires, vol. i. (1864-69), p. 173, pL v. 

 Fig. 8. 



