140 



ADDITIONS TO THE LIBRARY. 



Gray, G. H. Genera of Birds. 4to. Part 25. Courtis 

 Fund. 



American Journal of Science, for May, 1846. From the 

 Editors. 



American Quarterly Journal of Agriculture and Science. Vol. 

 III. No. 2. Albany : 1846. From the Editors, 



Proceedings of the American Philosophical Society, from Jan- 

 uary to April, 1846. From the Society. 



June 3, 1846. 



D. H. Storer, M. D., Vice President, in the Chair. 



Dr. J. B. S. Jackson directed the attention of the Society 

 to a statement made by Professor Owen, in regard to the 

 dentition of the Mastodon. (^Odontography, p. 615.) 



One of the distinctive characters, he says, is a displacement 

 of the first and second molars, in the vertical direction, by a 

 tooth which is developed above them in the upper, and below 

 them in the under jaw, and this has been recognized in the 

 M. giganteum and M. angustidens. In a note, however, at the 

 bottom of the page, he says : " The presence of the small pre- 

 molar in the lower jaw has not yet been determined ; neither 

 has its absence. An excavation in the jaw of the young mas- 

 todon, described by Dr. God man, at the place where the germ 

 of the premolar is hypothetically stated in PI. 144, fig. 7, b. 1, 

 would determine this point in regard to the M. giganteum.'^ 

 Dr. Jackson then showed the lower jaw of a young animal, from 

 the Mastodon Collection which is now at Cambridge, and in 

 which, as he formerly observed, (Proceedings of the Society, 

 October, 1845,) the first three molars are developed and above 

 the socket. Below the second of these teeth, and in the outside 



