331 



iVoni New Jlexico, doscrilx'd page 235, and i('[)ix\seiitcd in Figs. 1, 4, 

 Plate XXII, bears a veiy near resemblance vvitli the corresponding 

 part of the same tooth in the Mechoacan specimen. Notwithstanding 

 this likeness, it woidd appear that the fore part of the jaw differs so 

 much that tlie two may l)e supposed not to pertain to the same species. 

 As stated in the account of the New Mexico Mastodon, the anterior 

 extremity of the jaw is enormously prolonged and provided with a pair 

 of incisor's. Von Meyer observes of the Mechoacan specimen, "Too 

 little of the symphysis is preserved to speak with any certainty of its 

 constitution ; but it appears not to have contained incisors and rather 

 ended in front in a short beak, as in the elephant." The jaw he I'efers 

 with doubt to the Mastodon Humholdti. 



- I have said that -the New Mexican and Mechoacan specimens may be 

 supposed not to pertain to the same species. However, when we con- 

 sider the difference in the fore part of the lower jaw of the sexes in 

 the Mastodon americanus, it is not improbable that the male of the 

 Mastodon Shepardi may have had the lower jaw provided with a long 

 beak and incisors which might have been absent in the female. 



'&" 



UINTATHERIUM. 



Titanotlierium. Marsli : Am. Jour. Sc. 1S71, II, 35 ; the article published in 

 advance Juue 21, 1871 ; ibid. 1872, IV, 123, ijublished iu advance July 22, 

 1872. 



Mastodon. Marsh: Am. Joui-. Sc. 1872, note to p. 123, published iu advance 

 July 22, 1872. 



UlNTATHERIUM. 



Leidy: Pr. Ac. Nat. Sc. 1872, 1G9 ; in a letter addressed to the Academy and 

 published in advance of the proceedings August 1, 1872. Reprinted in Am. 

 Jour. Sc. September, 1872, 239. Pr. Ac. Nat. Sc. 1872, 241. Marsh: Pr. Am. 

 Phil. Soc. 1872, 578; Am. Jour. Sc. 1873, V, 118; American Naturalist 

 1873, 147. Cope: Pr. Ac. Nat. Sc. 1873, 10, 102; Pr. Am. Phil. Soc. Feb., 

 1873. Nature : March 13, 1873, 3GG. 



Uititamastix. Leidy : Pr. Ac. Nat. Sc. 1872, 169. 



Tinoceras. Marsh: Am. Jour. Sc. 1872, IV, in errata of Sept. No.; do., p. 504, 

 published in advance August 19, 1872; ibid. 1872, IV, 322, published in 

 advance August 24, 1872 ; ibid. 1872, IV, 323. published iu advance Sep- 

 tember 21, 1872; ibid. 1872, IV, 343, published in advance September 27, 

 1872; ibid. 1873, V, 117, published in advance January 28, 1873; ibid. 1873, 

 V, 293, published iu advance March' 18, 1873; American Naturalist Jan., 

 1873, 52. 



