MASTODON ANGUSTIDENS. 73 



also the first true molar behind it, the crown being entirely broken off, 

 but shown to be in germ. A portion of a grooved tusk is attached. If 

 of the lower jaw, it would be of left side. It corresponds very much 

 in size with the upper third molar above described in the principal 

 conglomerated specimen ; the vertical ridge is very well marked. 

 "Width of 1st ridge, about 2-2 in. Length of crown, about 3-3 in. 



The ridges are trenchant, and made up of about six points ; valleys 

 perfectly open ; the posterior talon has a crenulated bourrelet, as in 

 the small second milk upper of Mastodon latidens, but much less 

 developed. The two posterior ridges are very little touched by wear. 



B. Mastodon Angustidens. 



Winterthur, August 30, 1856. — Museum, of Mons. Johann Zlegler -Ernst. 



Got a note from Professor Heer, and visited M. Ziegler, who 

 showed me a superb specimen of the lower jaw, both sides nearly 

 complete (but broken up, the left side especially, into several fragments, 

 which fit together, and also to a large block of sandstone matrix), of a 

 half grown or younger individual of Mastodon angustidens. It exhibits 

 the milk-dentition, also one of the vertical premolars, both sides, and a 

 true molar embedded in the alveolus ; also a considerable portion of 

 the prolonged beak, which shows the transverse section of two very 

 compressed lower incisors. 



The following teeth are seen in succession : 



A. — An oval shaped bicuspid tooth with an entire crown, but chiefly 

 concealed in matrix, so that the top of it cannot be seen, only the side. 

 It resembles in form very much the small cuspid tooth seen in the 

 Museum at Zurich. By the section it is seen to have two compressed 

 fangs. The larger cusp is in front, the smaller behind ; but both are 

 partly concealed by matrix. 



The crown measures 12 inches in length. The posterior edge of the 

 anterior cusp is vertically lobed by three indentations. The crown 

 would appear to be quite entire and unworn. 



B. — A tooth of which the crown is entirely concealed in matrix, 

 but the side of the basal enamel is disclosed, and also the broken ivory 

 nucleus. This tooth presents two large and separated fangs : the 

 posterior being much the largest. Judging from the length, one would 

 almost suppose that it had three ridges; but this is unfortunately 

 concealed by matrix, nor is it visible what amount of wear it had 

 undergone ; it is assuredly a milk molar, from there being a vertical 

 premolar below it. 



Length of crown enamel, 2 - 4 in. 



C. — Immediately below this tooth and pushing it up is seen the germ 

 of a vertical premolar of large size (so to speak), exactly as in Lartet's 

 specimens in the Paris Museum. 



Length of this tooth so far as disclosed, 1/4 in. Height of anterior cusp, 1*1 in. 



D. — Immediately behind the tooth B is placed another molar (with 

 three ridges), of which on the left side the top of the crown is seen, but 

 the two anterior ridges are broken off. The posterior ridge and the 

 talon are quite entire. The last ridge has the tips of the tubercles just 



