Loomis — An Unusual Mastodon. 443 



upper molar has five transverse ridges and a talon, 

 whereas the usual number is four and a talon. The extra 

 ridge is unusual, but has been noted in the case of a 

 couple of specimens from Big Bone Lick, from one found 

 in Virginia, and in the case of the specimen described by 

 Holmes 7 from South Carolina. It seems to go with the 

 southern and larger forms. 



The lower jaws on the mounted skeleton are from the 

 Nine Mile Bottom individual. The fifth and sixth molars 

 are present on both sides. The fifth has three transverse 



Fig. 4. 



Fig. 4. The upper molars to show the five and the small talon. % nat. size. 



ridges, and is 104 mm. long by 88 mm. wide as compared 

 with 101 mm. by 77 mm. in the Warren mastodon. The 

 last lower molar is 191 mm. long by 94 wide, while that of 

 the Warren' mastodon is 193 mm. long and 77 mm. wide. 

 The Amherst tooth then is not quite so long but consid- 

 erably wider than in the Warren mastodon. However, 

 the Amherst mastodon is marked by having five trans- 

 verse ridges and a talon, against four and a talon on the 

 Warren tooth. This is the same increase in complexity 

 characteristic of the upper jaw. 



In general such a difference indicates a separate 

 species, but the mastodon had very wide range and I do 

 not favor splitting up the species unless there are sev- 

 eral characters differing, for wherever large series of 

 individuals have been studied dental variation of larger 

 amount than here found often appears, as in the case of 

 the skulls of the saber-toothed tigers from Rancho Le 

 Brea. This extra ridge is not a sexual feature, for some 

 of the tusked forms have only four; nor does it depend 

 entirely on size, for the Warren mastodon has only four 

 and is nearly as large. It looks like a meristic variation 

 which appears frequently among the American masto- 

 dons. 



T Post Pleiocene Fossils of South Carolina, 1860, p. 108, fig. 1, pi. 18. 



