FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



237 



foramen is generally beneath the posterior end of P3 or anterior end 

 of P4. The coronoid process seems to have been high and broad. 

 The masseteric fossa is shallow and simple, its only sharp boundary 

 anterior. The angle is poorly preserved but evidently was rounded 

 and not sharply projecting. The dental foramen is about on a level 

 with the alveolar border. The condyle is elevated well above the 

 teeth and its transversely oval, gently convex articular surface faces 

 equally posteriorly and superiorl3^ 



The infraorbital foramen is above P^, and the zj^goma arises chiefly 

 above M^. 



The statistical constants of the principal tooth dimensions are given 

 in table 51, based entirely on the sample from the Gidley Quarry. 



Table 51. — Numerical data on upper and lower dentition of Ellipsodon aquilonius 



Variate 



LP,- 

 WP3- 

 LP,.. 

 WP4- 

 LMi. 

 WMi 

 LMo_ 

 WM2 

 LM3. 

 WM3, 

 LP3__ 

 WP^ 

 LP<._ 

 WPi. 

 LML 

 WM> 

 LM2_ 

 WM2 

 LM3. 

 WM2 



N 



10 

 10 

 10 



11 



19 



19 



28 



29 



24 



24 



6 



7 



7 



7 



10 



10 



13 



13 



8 



9 



R 



8-3. 5 

 7-2. 1 

 2-3. 7 

 1-2. 5 

 1-3. 6 

 7-3. 2 

 1-3. 9 

 8-3. 6 

 5-4. 1 

 4-3. 

 1-3. 3 

 5-2. 9 

 0-3. 2 

 8-4. 1 

 1-3. 4 

 1-4. 5 

 1-3. 7 

 9-5. 4 

 3-2. 6 

 5-4. 1 



U 



3. 22 ±0.06 



1. SS±0. 03 

 3. 41 ±0. 05 



2. 31 ±0. 04 



3. 40 iO. 03 



2. 90 ±0. 04 



3. 58 ± 0. 03 

 3. 30 iO. 04 

 3. 82 ±0. 03 



2. 75 ±0. 03 



3. 23 ±0. 03 



2. 71 ±0. 06 



3. 11 ±0. 024 

 3. 96 ±0. 04 



3. 21 ±0.03 



4. 29 ±0. 05 

 .3. 43 ±0. 05 



5. 20 ±0. 05 



2. 40 ±0. 04 



3. 71 ±0.07 



0. 19 ±0. 04 

 0. 108±0. 024 

 0. 16 ±0. 04 

 0. 116±0. 025 

 0. 143 ±0. 023 

 0. 172 ±0. 028 

 0. 179±0. 024 

 0. 1 90 ± 0. 025 

 0. 134±0. 019 

 0. ]61±0. 023 

 0. 075 ±0. 022 

 0. 15 ±0. 04 

 0. 064 ±0. 017 

 0. 12 ±0. 03 

 0. 104±0. 023 

 0. 14 ±0.03 

 0. 17 ±0.03 

 0. 17 ±0. 03 

 0. 100±0. 025 

 0. 21 ±0. 05 



6. 0±1. 3 



3. 7±0. 8 



4. 6±1. 



5. 0±1. 1 



4. 2±0. 7 



5. 9±1. 

 5. 0±0. 7 

 5. 8±0. 8 

 3. 5 ± 0. 5 

 5. 8±0. 8 

 2. 3±0. 7 

 5. 4±1. 4 



2. 1±0. 6 



3. 0±0. 8 

 3. 3±0. 7 



3. 4±0. 8 



4. 9±1. 1 



3. 2±0. 6 



4. 2±1. 



5. 6±1. 3 



Despite the fact that the sam.ple probably includes both sexes and 

 certainly includes teeth in many different stages of wear, the figures 

 are very consistent and show remarkably little variation. The high- 

 est V is only 6.0 and the average is 4.35. The consistent distribution 

 of the V's is also striking, for of the 20 values only two differ from 

 the average by as much as twice the corresponding standard error. 

 The two exceptions (for length of P^ and length of P^) are based on 

 scanty data and are abnormally low values, 2.3 and 2.1. 



The unusually adequate sample of E. aquilonius from the Gidley 

 Quarry and the presence of seven lower jaws apparently of the same 

 species from the Silberling Quarry afford the best opportunity to 

 detect any minor differences that might occur between these two 

 horizons and localities. The possible association of morphological 



