14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 66 



molar of the Navasota mastodon is only 6 mm, shorter and 7 

 mm. narrower than Cope's type. The principal known difference 

 between Cope's Mastodon serridens and the form cimarronis is that 

 the former is much larger. The type of serridens was taken to be a 

 first or second molar whose length is 130 mm. The length of the 

 upper second molar of the Navasota mastodon is only 105 mm. It 

 does not show the original condition of the grinding surface; but 

 the hindmost molar does this; and the cross-crests and the but- 

 tresses present nearly the same tuberculated condition as does the 

 type of Cope's Mastodon serridens. The differences in the tubercu- 

 lation of the two forms as pointed out by Cope are probably of 

 minor importance. 



Schlesinger ^^ describes a form of mastodon to which he gave the 

 name Mastodon angustidens siibtapiroidea. This resembles in many 

 respects the G. cimarronis^ so far at least as regards the molars ; but 

 the latter species appears to be more advanced. If they should be 

 shown to be identical forms, cimarronis would supersede suhtapi- 

 roideus. Gom,photherium cimarronis differs from G. productum in 

 that the teeth are less hypsodont. 



EXPLANATION OF PLATES 



Plate 1 



Anancus brazosius 



View of occlusal surface of the right lower third molar. X.83. No. 41652. 

 British Museum of Natural History. 



Plate 2 



Anancus brazosius 



Fig. 1. Same tooth as that figured on Plate 1. X .47. 



2. Mandible and third molar from Cameron, seen from lingual side. X.21 



Plate 3 

 Anancus brazosius 



Fig. 1. Same mandible and molar as that of Figure 2 of Plate 2, seen from 

 above. X .46. 



Gomphotherium cimarronis 



Figs. 2, 3. Lower right and left third premolars. X .96. 



2. Left seen from above. 



3. Right seen from the lingual side. 



4. Upper right second molar. X .5. View of occlusal surface. 



5. Upper right third molar. X.5. Shows occlusal surface. 



6. Lower left third molar. X..5. Shows occlusal surface. 



"> Denksehr. Naturh. Staatsmus., Vieima, vol. 1, pp. 30-38, pi. 7, fig. 3. 



