FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



263 



The general statistical data on the simple dimensions of the lower 

 teeth of all Torrejon specimens of Anisonchus sectorius in the American 

 Museum are presented in table 61. 



Table 61. — Numerical data on lower dentition of Anisonchus sectorius 



The lower dentition material from the Crazy Mountain Field now 

 available consists of three specimens from the Gidley Quarry, three 

 from Loc. 25, four from Loc. 51, and one each from Locs. 50 and 18. 

 The highest number of comparable specimens from a single horizon 

 and locality is only three, for P4 from the Gidley Quarry. 



10- 



"> 



'13 



c 



4.9 



— I — 

 5.2 



5.5 5.8 



— I — 



6.1 



LENGTH Ml 



Figure 79.— Histogram of the length of Mi In Anisonchus sectorius (Cope): In solid outline, Torrejon speci- 

 mens (American Museum); in dotted outline, Lebo specimens (National Museum). 



By inspection of the specimens and of their dimensions, it is sug- 

 gested that there is local differentiation. Thus in the series from the 

 Gidley Quarry, Loc. 25, and Loc. 51, each local sample seems to be 

 reasonably homogeneous and to differ slightly from that of the other 

 two localities. In the jaws from the Gidley Quarry the lower molars 

 are longer, but not noticeably wider, than those from Loc. 25. The 

 very poor material from Loc. 51 suggests closer agreement mth the 

 Gidley Quarry at least in P4 and Mj, but two isolated Mg's from there 



119212—37 18 



