FORT UNION OF CFwAZY MOUNTAIN FIELD, MONT. 



245 



Table 55. — Principal available numerical data on lower dentition of Haplaletes 

 disceptatrix, all from the Gidley Quarry 



Varinte 



LP3- 

 WP3 

 LP4. 

 WP4 

 LM, 

 WM 

 LM2 

 WM 

 LMn 

 WM 



N 



S(d2) 



0. 0200 

 0. 0200 

 



0. 0050 

 0. 0276 

 0. 0276 

 0. 1350 

 0. 1006 

 0. 0800 

 0. 0286 



P^ is a small simple tooth resembling an anterior lower premolar. 

 P^ is peculiar in having a low and small but sharp and distinct proto- 

 cone. P^~* resemble those of Litaletes in their rudimentary metacones, 

 but the metastyles are less developed, and P"* has no metaconule. The 

 upper molars are similar to those of Litomylus, but are more rounded 

 in contour and have the hypocones of M^~^ smaller. 



P3 has a distinct paraconid and a heel about as well developed as that 

 of P4 in most contemporaneous species. P4 has definite paraconid 

 and m-ctaconid and a wide, large, basined heel with two posterior 

 cusps. The lower molars resemble those of Litomylus, but the crowns 

 are lower, the cusps blunter, and the internal cusps more distinctly 

 elevated over the external. The talonid of M3 is less elongate. 



Family PHENACODONTIDAE Cope, 1881 



Most of the manuscript notes left hj Dr. Gidley refer to this group, 

 and it was evidently his intention to publish a prehminary paper on 

 it. There are three different drafts of part of his brief account, 

 evidently written at different times and in part not consistent with 

 one another. The draft that seems to be most recent is still mcom- 

 plete and has still later memoranda written on it for other changes 

 that were never made. The integral publication of this manuscript 

 is impossible, as it does not form a connected whole and does not fairly 



