1899.] NEOMYLODON LISTAl FROM PATAGONIA. 151 



lacunae. Nearly everywhere, except in the narrow peripheral area 

 just mentioned, it is easy to recognize the bouy laminte arranged 

 in Haversian systems round the canals ; and most of the lacuna? 

 between these laminfe are excessively elongated, with very numerous 

 branching canaliculi, which extend at right angles to their longer 

 axis. Near the margin of the ossicle, especially in its more trans- 

 lucent parts, the bone-lacunae are less elongated, more irregular in 

 shape, and apparently not arrangr'd in any definite order (PI. XV. 

 fig. 7 h). There is no clear evidence of bony laminae concentric 

 with the outer margin, though appearances are sometimes sugges- 

 tive of this arrangement. A vertical section of an ossicle presents 

 exactly the same features as the horizontal section now described. 

 It is thus evident that the vascular canals with their Haversian 

 systems of bone have no definite direction, but are disposed in an 

 entirely irregular manner. 



Taking into consideration all characters, and making comparisons 

 with the aid of my friend Mr. W. E. de Winton, I am inclined to 

 regard the fragmentary specimen as the skin of the neck and 

 shoulder- region with part of the left cheek. The apparent bilateral 

 symmetry between at least part of the thickened anterior outer 

 angles of the specimen has already been noted ; and if this obser- 

 vation be well-founded, the middle line of the back extends verti- 

 cally down the middle of the figure, PI. XIII. If the rounded 

 notch above B be the base of the external ear, as seems probable, 

 the thick wrinkled skin (C) with fine short hair still further to 

 the left must be the cheek. The ear and cheek on the right side 

 have been removed ; but at the base of the outwardly-turned angle 

 on this side of the specimen there are the very long hairs which 

 occupy a similar position on the left. It thus seems possible to 

 estimate the transverse measurement between the ears as from 

 0"25 m. to 0*30 m., which corresponds with a tentative estimate of 

 the same distance in Mylodon rohustus based on a skull in the 

 British Museum. 



(b) Comparisons and General Conclusions. 



The skin now described ditfers from that of all known terrestrial 

 Mammalia, except certain Edentata, in the presence of a bony 

 dermal armour. There can therefore be little doubt that the 

 specimen has been rightly referred to a member of this typically 

 South-American order. Even among the Edentates, however, the 

 fragment now under consideration is unique in one respect ; for 

 all the ossicles are buried deeply in the 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 ssparate 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 



