128 DISTINCTION INTO. SPECIES. 



Mastodon however, we have not a sufficient number of facts to warrant a decided 



Angusti- 



dens. conclusion. 



The nineteenth dorsal vertebra is said to be the last rib-bearing, and 

 in consequence there are four lumbar vertebrae, while in the Mastodon 

 Giganteus there are three. The humerus is much shorter, more clumsy 

 and twisted than in the Mastodon Giganteus. The femur has its third 

 trochanter more prominent ; the articulating surface for the patella is one- 

 third smaller. 



The bones of the Mastodon Angustidens, according to the same author, 



■ 



seem to have a greater resemblance to those of the Asiatic Elephant than 

 to those of the Mastodon Giganteus. The most important differences are 

 in the teeth, on which, as already said, is founded the name Angustidens, 

 or narrow tooth. Through the intervention of my friend Dr. Boott, I have 

 received, by the politeness of Charles Stokes, Esq. of London, casts of two 

 large molars, one of them said to belong to Mastodon Longirostris, the 

 other to Mastodon Angustidens ; and also, through that of the late Professor 

 De Blainville, a complete set of all the teeth in the upper and lower jaw, 

 marked Angustidens in the National Museum of Paris. Besides these, I 

 have some Angustidens teeth which I purchased in Paris in 1851, and the 

 cast of a beautiful ultimate molar given me by M. Laurillard as such. 



The incisors are two in the upper, and two in the lower jaw. The first 

 molar is similar to the small deciduous molar of the Mastodon Giganteus. 

 The second molar has three instead of two ridges. The third is peculiar, 

 being the vertical tooth in the upper jaw mentioned by Professor Owen. 

 This vertical premolar has not been admitted by De Blainville. The three 

 following teeth have been variously viewed by different writers : some con- 

 sider them as possessed of three ridges, and others assign to a part or the 



