3IO UNIVERSITY OF COLORADO STUDIES 



but in Mr. Brown's Paramylodon there were only four, this being one 

 of the principal characters upon which the new genus was based. It 

 seemed possible that the type of Paramylodon had lost the anterior 

 tooth, which is a short distance from the others, and not strictly in a 

 line with them. If this could be believed, the other differences might 

 be attributed to individual variation, and the animals referred to the 

 same species. 



At this point, photographs of our specimen were sent to Mr. Brown, 

 together with a statement of the difficulties encountered. He has very 

 kindly made comparisons, and has written as follows: 



Our Paramylodon skull is perfect. Not any of the palate has been broken away, 

 and there never were but four teeth on a side. In Edentates the contour of the 

 tooth is accurately defined by the alveolus, so we are pretty safe in comparing the 

 two skulls that way. Thus in the two skulls the pattern of teeth is similar if not 

 identical in the last four. The dental series in your skull, however, seems much 

 farther forward, and presumably the teeth are smaller. The distance from the 

 last molar to the post-palatine notch is greater in your skull; condyles are wider 

 apart and placed parallel with axis of skull as in South American Mylodons. Our 

 skull is narrower across orbits and occipital region is narrower; musculature not 

 so well defined. Shortly after I published, Harvard University secured a nearly 

 complete skeleton of Mylodon from the same Hay Spring region, and I believe it 

 is the same species that you have. (April 10, 1909.) 



I also sent photographs of the Colorado skull to Dr. Chas. W.Andrews, 

 of the British Museum, who replied that so far as he could judge from 

 them, he could not see why the animal should be separated from Mylodon. 

 The total length of our skull is 540 mm., and the width of the muzzle at 

 its widest part is 150, or a trifle less. The animal was doubtless as 

 large as a rhinoceros. The first upper tooth is very much smaller than 

 the second, and is placed 6^ mm. from it. The socket is oval in outline, 

 with the greater diameter 22 mm.; only a portion of the root of the 

 tooth remains. The other teeth, judging from the sockets, were in 

 exact agreement with Paramylodon. 



The measurements of the alveoli of four last teeth (corresponding 

 with those present in Paramylodon) are as follows: (1) long. 37, lat. 

 19 mm.; (2) long. 38, lat. 30 mm.; (3) long. 34, lat. 22 mm.; (4) long. 



