2 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.66 



second, and third crests are furnished with buttresses, narrow front 

 and aft, which do not meet to close the valleys, but which, at a 

 medium stage of wear, would produce trefoils. The basal lobes of 

 these would naturally be smaller than those of the outer trefoils. 



In the United States National Museum is also a cast, the gift 

 of the British Museum of Natural History, of the left ramus of the 

 lower jaw figured in Falconer and Cautley's Fauna Antiqua Sival- 

 ensis (on pi. 35, figs. 3 and 3«). This jaw was obtained in the 

 Pleistocene of Buenos Aires, and on the plate cited was referred 

 to as Mastodon andium; but in 1886 it was identified by Lydekker ^ 

 as M. humholdtii. This species has been supposed to be distinguished 

 from BI. andiuni by the presence of trefoils on both ends of the 

 crests, but the character is now recognized as variable. The but- 

 tresses of the inner ends of the crests of the Texas specimen are 

 more prominent than those of the jaw from Buenos Aires. The 

 writer does not see, therefore, why the Texas molar should not 

 be referred rather to M. hwniholdtii than to M. cordUlervmi. The 

 latter name is that employed by Lydekker for the mastodon called 

 by other authors M. andium or M. cordillerarum. 



2. On a lower jaw fodnd at Cameron, Texas 



From Dr. Mark Francis, of the Texas Mechanical and Agricul- 

 tural College, College Station, Texas, the writer received in August, 

 1923, for examination, the horizontal portion of the left ramus of 

 a lower jaw of a mastodon whose teeth present trefoils. This jaw 

 was found in 1897, in a gravel pit near Cameron. From Judge 

 Jeff T. Kemp, of Cameron, it is learned that the gravel pit was about 

 2 miles north of Cameron, at a height of between 40 and 50 feet 

 above high water in Little River. The bone of this jaw extends 

 from the symphysis to a short distance behind the third molar. The 

 symphyseal region is injured and somewhat waterworn. The bone 

 on the inner face was broken away so that the hinder root of the great 

 molar was exposed. An additional part was lifted by the writer, 

 in order to expose the other fangs (pi. 2, fig. 2; pi. 3, fig. 1). As 

 to the dimensions of the jaw, the distance from the hinder end of 

 the last molar to the hinder end of the symphysis was close to 235 

 mm. The depth of the ramus at the middle of the last molar is 

 160 mm.; the thickness, 138 mm.; the height at the front of the 

 socket for the second molar is 190 mm. 



In this mandible is present the socket for the second molar. This 

 molar may have fallen out just before the death of the animal or 

 afterwards. The cavity for its anterior fang is 50 mm. or more 

 deep. The hinder fang must have been mostly absorbed. From the 



2 Cat. Foss. Mainin. Brit. Mus., pt. 4, p. 42. 



