364 BUREAU OF AMEEICAN ETHNOLOGY [bull. 52 



formation may be burnt without the agency of man, and he does not 

 attach any significance to the occurrence of burnt earth as an evidence 

 of man's existence in the Miocene ( ?) "Monte Hermosean." 



Examination op the Skeletal Parts Attributed to the Tetraprothomo 



By AleS Hrducka 

 THE MONTE HEEMOSO ATLAS 



The bone comes apparently from an adult subject. 



In color it is now shiny brownish-black, but this is due to it having 

 been treated with melted wax and resin. According to the museum 

 preparator and others who saw the bone before it was thus treated, 

 its color was yellowish or yellowish-brown, "like that of an ordinary 

 earth." 



Owing to the wax and resin it can not now be seen whether or not 

 the bone was mineralized, or, if mineralized, to what extent. How- 

 ever, it is not heavy, and in knocldng it against the teeth it gives much 

 the same sound as would an atlas from a moderately old grave. 



The bone is submedium in size and rather massive, but is in 

 every respect human. An extensive comparison lAdth human and 

 other mammalian atlases settles its human provenience beyond 

 question. It is more or less distant morphologically from the atlases 

 of all the anthropoid apes and still more so from those of the monkeys, 

 while the atlases of the Carmvora and other mammals present such 

 differences that a comparison becomes entirely superfluous. 



The specimen looks really smaller than it is, owing to the defective 

 state of the lateral processes. It measures 3.85 cm. in greatest 

 antero-posterior diameter^ and was near 7 cm. in greatest 

 breadth, exceeding in both dimensions five and equalling one of the 

 Indian atlases from the series of 100 selected at random and used 

 by the writer for comparison (pi. 59). The smallest normal adult 

 atlas in this series measures 3.5 b}' 6.4 cm. Macalister- determined 

 that the female atlas averages 4.2 by 7 cm., while the smallest 

 adult specimen in his collection was only 3.6 by 6.1 cm. 



The central aperture even more than the whole specimen gives the 

 impression of being undersized. Tliis is due partly to the optical 

 effect of the rather stout arches and lateral masses which surround 

 it, and partly to an encroachment on its lumen of the lateral masses. 

 The actual measurements of the aperture, however, show that while 

 submedium, it is by no means outside of the range of size variation of 



1 A cast of the atlas, donated hy Professor Ameghino to the United States National Museum, while 

 seemingly accurate as to form, presents in general slightly greater dimensions than the original. This is 

 doubtless the fault of the artist or of the material, but the fact should be liorne in mind by those who may 

 desire to utilize any measurements on similar casts. All the measurements of the atlas given in this report 

 were made on the original. 



2 Macalister, A., Notes on the Development and Variations of the Atlas; in Jour. Anat. and Physiol., 

 xxvn, London, 1S93, pp. 519-542. 



