146 



Citing the American authorities on his side of the question, in- 

 cluding Dr. Hayes, and enumerating no less than thirteen species of 

 Mastodon and six species of Tetracaulodon, Dr. Grant has made a 

 vigorous effort to vindicate the true generic characters of the Te- 

 tracaulodon as founded ou the presence of a tusk or tusks in the 

 lower jaw and certain variations in the form of the crowns of the 

 molar teeth. 



This view has been sustained bj^ Mr. A. Nasmyth in an elaborate 

 paper '•' On the Minute Structure of the tusks of extinct Masto- 

 dontoid animals." Microscopical examination of portions of the tusks 

 believed to belong to five distinct species, viz. Mastodon giganteus, 

 Tetracaulodon Godmani, T. Kochii, T. Tapiroides and the Mis- 

 soui'ium, 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 paleeontological science. 



Professor Owen had previously expressed opinions at variance 

 with those of Drs. Hayes, Godman and Grant and Mr. Nasmyth, 

 and his views have been supported within these Avails by my pre- 

 decessor, Dr, Buckland. Pointing out certain mistakes in the set- 

 ting up of the Missourium, as exhibited in the Egyptiaff Hall, he 

 compares the fossil with all forms with which he was acquainted ; 

 and, showing that it must have belonged to the Ungulata, he judges 

 that the enormous tusks of the upper jaw constitute it 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 pro- 

 boscidian, and that Mr. W. Cooper was correct in suggesting that 

 the Tetracaulodon was nothing but the young of the gigantic Mas- 

 todon, 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 Blephas primigenius (Mammoth), all the other remains of 

 proboscidean pachyderms in it belong to the Mastodon giganteus. 

 The remains of other animals found by M. Koch are referred by 

 the Hunterian Professor to Lophiodon, Mylodon Harlani, JBos, 

 Cervusi &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 right lower tusk only in the adult male. Although 

 unable to form a correct judgement on the probable structure of 

 those extinct quadrupeds, I may call your attention 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, the same views as Professor Owen 

 concerning the osteology and generic characters of the Mastodon 

 founded upon the comparison of a series of bones and teeth belong- 

 ing to the Mastodon longirostriSf more numerous and complete than 

 even those of the Mastodon giganteus. 



