156 ON IVEOMYLODON LISTAI FROM PATAGONIA. [Feb. 21, 



problematical skin mentioned by Dr. Moreno as having been taken 

 to Upsala by Dr. Otto Nordenskjold \ It appears that with the 

 skin was found the epidermal sheath of a large unknown claw, which 

 may have belonged to the same animal. This specimen proves to 

 be different from that of any existing Sloth, Anteater, or Armadillo, 

 and is considered by Dr. Lonnberg to belong probably to the hind 

 foot of a Mylodont, which did not walk on the exterior, lateral 

 surfaces of the toes to the same extent as Mylodon. In a section 

 of the skin provisionally ascribed to the leg, he observes that the 

 small ossicles are A^ery irregular, and shows two instances in which 

 two are placed one above the other. In microscopical sections 

 of the ossicles, however, he does not find the distinct Haversian 

 systems of bone so conspicuous in my slides ; and hence he fails 

 to remark the differences between the structure of the armour in 

 Neomylodon and Mylodon, which seem to me to be particularly 

 noteworthy. His so-called " pigment cellules " in Mylodon are 

 the dendritic infiltrations of oxide of manganese and sfains of 

 oxide of iron, to which I have made special reference. His 

 observations as to the absence of a medulla in the hair confirm my 

 own ; but I have not seen any evidence of the suspected loss or 

 disintegration of the hair-cuticle. Tinally, Dr. Lonnberg has 

 boiled a piece of the skin, thereby extracting glue, " which proves 

 that the collagen and gelatinous substances are perfectly preserved." 

 The latter observation confirms the evidence of the serum recorded 

 above, and indicates that if the specimen is " of any considerable 

 age, it must have been very well protected against moisture and 

 bacteria."— A. S. W.] 



EXPLANATION OF THE PLATES. 



Plate XIII. 

 Neomylodon listai, Ameghino ; outer aspect of piece of skin, one half nat. size. 



Plate XIV. 

 D itto ; inner aspect of same specimen, one half nat. size. 



Plate XV. 

 Pig. 1. Neomylodon listai, Ameghino; transverse section of skin, nat. size, 

 showing hair above and ossicles in lower layer. 

 2, 3. Ditto ; outer face of two ossicles, nat. size. 



4-6. Mylodon, sp. ; outer face of three ossicles, nat. size, one composed of 

 two parts fused together. 4 a, 4 5. Inner and lateral aspect 

 respectively of the specimen shown in fig. 4. 



7. Neomylodon listai, Avaeghmo ; portion of horizontal section of ossicle, 



about X40. 7 a, 7 b. Haversian system and two mai'ginal bone- 

 lacunse from the same, respectively X 85 and X 200. 



8. Mylodon, sp. ; portion of horizontal section of ossicle, about X 40. 



8 a. Three boue-lacunaj from the same, X 200. 



1 E. Lonnberg, " On some Remains of ' Neomylodon listai' Ameghino, 

 brought home by the Swedish Expedition to Tierra del Fuego, 1895-1897," 

 Wissensch. Ergebn. schwedisch. Exped. Magellansland. unter Leitung v. Otto 

 Nordenskjold, vol. ii. pp. 149-170, pis. xii.-xiv. (1899). 



