38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I44 



larger size of P4 is rather suggestive of Lost Cabin Absarokius 

 noctivagns. This combination of characters indicates, if the horizon 

 is correctly recorded, that the development of P4 may be rather 

 variable and not so orderly with respect to horizons of Wasatchian 

 time. 



The University of Wyoming specimen has two incisor alveoli, the 

 first of which may be a trifle larger and more nearly circular in out- 

 line than the second. The canine alveolus is distinctly larger than that 

 for the second incisor but evidently no greater is size than that for the 

 anterior root of P3. None of these are comparable to that for the 

 enlarged anterior tooth in Tetonius. Between the canine alveolus and 

 the anterior root of P3 there may possibly be an extremely flattened 

 alveolus for a P2, only slightly narrower transversely than that for the 

 canine. P3 would appear from outside the jaw to have two well-defined 

 roots. 



MEASUREMENTS IN MILLIMETERS OF TEETH IN LOWER JAW OF 



Absarokius, near A. abbotti, u. of wyo. no. 1644 



M1-M3, length of lower molars 



P3, anteroposterior diameter : transverse diameter at cingulum . 

 P*, anteroposterior diameter : transverse diameter at cingulum., 

 Ml, anteroposterior diameter : transverse diameter at cingulum. 

 M2, anteroposterior diameter : transverse diameter at cingulum. 

 M3, anteroposterior diameter : transverse diameter at cingulum . 



6.1 



1.5:1.8 

 2.4 : 2.5 

 2.3:1.8 

 2.0 : 1.7 

 2.1 : 1.4 



ABSAROKIUS NOCTIVAGUS Matthew 

 (Plate 4, figure i) 



Among the more recently acquired materials representing Ab- 

 sarokius noctivagus is a maxilla (U.S.N.M. No. 22264) with 

 p3.]V[3 from the locality 12 miles north of Big Piney. P^, a very 

 small, peglike tooth, was present in maxilla when found, but unfortu- 

 nately it has since been lost. P^, much smaller than P*, is seen to be 

 three-rooted with a prominent deuterocone and the talon is somewhat 

 expanded posteriorly, almost as in P*. This specimen, as well as the 

 immature lower jaw previously described (1952, p. 24), was dis- 

 cussed in 1958 (pp. 73-74) in connection with the possible dental 

 formula characterizing anaptomorphids. The lower jaw was illus- 

 trated in 1958 (pi. 14, fig. 8), whereas a drawing of the upper denti- 

 tion is included here (pi. 4, fig. i). 



ABSAROiaUS WITTERI Morris 



The Cathedral Bluffs species described by Morris is clearly larger 

 and with a more inflated-appearing P4 than in Absarokius noctivagus. 



