112 STUDIES IN TASMANIAN MAMMALS, LIVING AND EXTINCT. 



The reasons for opposing the Rhinoceros habit, in N 

 tasmanicum, as also the evidence in favour of the same, 

 in the light of information supplied by the study of the 

 skeleton of Nototherium mitchelli, have been duly set out, 

 in our Paper No. 3, and therefore need not be recalled 

 here. As far as we know, we have fairly impartially 

 weighed every fact of importance recorded by any and 

 all workers, in this particular branch of Palaeontology, and 

 the final result has been the several views expressed in our 

 short series of papers, of which the present constitutes No. 

 4. 



For the scientific vise of the skeleton at N ototheriun* 

 mitchelli, we are indebted to Mr. K. M. Harrisson, of 

 Smithton, who generously placed the specimens at our 

 disposal for the purpose named. Mr. Harrisson has also 

 presented the whole of the remains to the Tasmanian 

 Museum, Hobart, with a view to their future exhibition 

 at that institution. In conclusion, we may just add that 

 the order in which the osteological evidc nee has been re- 

 viewed was largely detex-mined by the condition of the 

 material — some bones being unfit to handle for months, 

 while ethers were stable at an earlier date. 



ADDENDUM. 



After our notes upon the nasal ossicles, found in the 

 skulls of the Nototheria, were in print we discovered that 

 similar structures) had been recorded, by Prof. O. C. Marsh, 

 as appearing in the gigantic Dinocerata, of Eocene, 

 North America. Prof. Marsh published his note in 1884 

 (U.S. Geological Survey, monograph No. 10, page 14), and 

 regarded the structures as being quite unique, but sug- 

 gested that they had survived in a modified state in the 

 modern artiodactyla as the p re-nasals of the genus ' us. 

 Obviously, if this homology is correct, the ossicles must 

 have been developed as a common ungulate possession 

 prior to the divergence of the perissodaotyla from the 

 artiodactyla, as it is unlikely they were separately evolved. 

 The parellel development of such structures in the Noto- 

 theria is an exceedingly interesting point, as also is the 

 appearance of a single central ossicle in the South Ameri- 

 can Mylodon — as duly noted in our text. 



The teeth of Tinoceras stenops, figured by Marsh 

 at page 47 of his monograph, show a disproportion be- 

 tween the upper and lower premolars, that is almost simi- 

 lar to that obtaining in the Nototheria. The cusping, of 

 course, is quite different. 



