78 on remains of OETPOTHEBiuM (neomylodon) listai. [Jan. 23, 



has shown that when bones are buried in ordinary sediments they 

 undergo changes which gradually cause the percentage of contained 

 fluorine to increase. According to him, the longer a bone has been 

 buried, the greater is the percentage of fluorine found in it on 

 analysis. In one case ' he examined the scapula of a deer and a 

 human tibia, discovered together in fluviatile sand near Billancourt 

 (Seine) ; he found that the former had 7 or 8 times its usual 

 percentage of fluorine, while the human bone did not differ in any 

 respect from the normal in this constituent. He therefore 

 concluded that the latter bone was not of the same age as the 

 former, but had been introduced comparatively recently by burial. 

 In this and the other recorded cases, however, it is to be observed 

 that the sediment was of a uniform character and admitted of free 

 percolation of water. In the Patagonian cavern, on the contrary, 

 the bones occur partly in dust, partly in dried herbage, partly 

 in dried excrement, and partly in the burnt residue of the same. 

 Moreover, they must always have been subjected to intense 

 dryness, and the usual process of chemical alteration cannot have 

 taken place. 



Considering all circumstances, I think that, even without 

 chemical evidence, zoologists and geologists cannot fail now to 

 agree with Dr. Moreno and his colleagues of the La Plata 

 Museum, that the remarkably preserved Orypotherhnn from the 

 Patagonian cavern belongs to the extinct Pampean fauna of South 

 America and need not be searched for in the unexplored wilds of 

 that continent. If we accept the confirmatory evidence afforded by 

 Mr. Spencer Moore, we can also hardly refuse to believe that this 

 great Ground-Sloth was actually kept and fed by an early race 

 of man. 



EXPLANATION OF THE PLATES. 



Plate V. 



Pig;. I. Grypotherium listai ; hinder portion of cranium, right lateral and 

 inferior (la) aspects, and in median longitudinal section (lb), nearly 

 one-half nat. size, b.s., basisphenoid ; /*., anterior condyloid foramen ; 

 m., facette for stylohyal ; p.s., presphenoid ; pt., pterygoid ; t., tympanic. 



2. Ditto; portion of right facial region, nearly one-half nat. size. 



3. Ditto ; anterior portion of nasal arcade, right lateral and anterior (3 a) 



aspects, nearly one-half nat. size, na., nasal bones ; .r, ossification in 

 internasal septum. 



Plate VI. 



Fig. 1. Grypotherium listai; right malar bone, outer aspect, one-half nat. size. 



2. Ditto ; portion of right mandibular ramus, inner aspect, and dentition 

 of left ramus, oral aspect (2 a), one-half nat. size. 



.'!. Ditto ; dentition of another left mandibular ramus, oral aspect, one- 

 half nat. size 



4. Ditto ; auditory ossicles of right side of skull no. 1, twice nat. size. 



/., incus, inside view ; m., malleus, outside view ; &, stapes, outside 

 view ; x, facette. 

 4«. Ditto; incus of left side of skull no. 2, inside view, twice nat. size, 

 showing orbicular bone (o.) attached. 



1 A. Carnot, " Sur une Application de 1' Analyse chimique pour fixer TAge 

 d'Ossements humains pr^historiques," Comptes Kendus, vol. cxv. (1892) 

 pp. 337-339. 



