On Mastodontoid and Megatherioid AnimaU. 181 



T. Tapiroides and the Missourium^ has also led this author 

 to the same inference as Dr Grant ; and he concludes with 

 the remark, that, if it be established that specific differences 

 positively do exist among all these animals, the value of such 

 microscopic researches is great ; but if the five animals are 

 grouped as one, then such mode of observation is of no value 

 in palaeontological science. 



Professor Owen had previously expressed opinions at vari- 

 ance with those of Drs Hayes, Godman, and Grant, and Mr 

 Nasmyth, and his views have been supported within these 

 walls by my predecessor, Dr Buckland. Pointing out certain 

 mistakes in the setting up of the Missourium, as exhibited in 

 the Egyptian Hall, he compares the fossil with all forms with 

 which he was acquainted ; and, shewing that it must have be- 

 longed to the Ungulata, he judges that the enormous tusks 

 of the upper jaw constitute a member of the proboscidian 

 group of pachyderms, and that the molar teeth prove it to be 

 identical with Tetracaulodon or Mastodon giganteus. He 

 argues that the genus Tetracaulodon was erroneously founded 

 upon dental appearances in the lower jaw of a very young 

 proboscidian, and that Mr W. Cooper was correct in suggest- 

 ing that the Tetracaulodon was nothing but the young of the 

 gigantic Mastodon, the tusks of which were lost as the animal 

 advanced in age. A comparison of the whole of M. Koch's 

 collection produced the result in Mr Owen's mind, that, with 

 the exception of a few bones of the Elephas primigenius (Mam- 

 moth), all the other remains of proboscidian pachyderms in 

 it belong to the Mastodon giganteus. The remains of other 

 animals found by M. Koch are referred to by the Hunterian 

 Professor to Lophiodon, Mylodon Harlani^ Bos, Gervus, &c. ; 

 and in respect to the Mastodon giganteus he expresses his 

 conviction that it had two lower tusks originally in both 

 sexes, and retained the lower tusk only in the adult male. 

 Although unable to form a correct judgment on the probable 

 structure of those extinct quadrupeds, I may call your atten- 

 tion to a recent work of Mr Kaup, whose striking discovery 

 of the Deinotherium is familiar to you, and who now seems 

 to advocate, from perfectly independent sources of evidence. 



