38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



scaphiciis, the larger, is represented at the saddle locality by the type 

 specimen, and at the ledge locality, about one-quarter mile to the west, 

 by a second jaw portion, U.S.N.M. No. 21015, almost identical to it. 



An upper molar, U.S.N.M. No. 21013, possibly M^ from the saddle 

 locality is structurally very much like the first or second upper molars 

 in L. dissentaneus, except that the protoconule and metaconule are 

 less well defined. 



Measurements of the teeth of this form are included with those of 

 the following species. 



LITOMYLUS SCAPHISCUS,!" new species 

 Plate 8, figure 5 



Type. — Right ramus of mandible with P3, Mi and M2, U.S.N.M. 

 No. 21010. 



Horizon and locality. — Bison basin Tiffanian, ledge locality at south 

 rim of Bison basin, W^ sec. 28, T. 27 N., R. 95 W., Fremont County, 

 Wyo. 



Specific characters. — Size of teeth close to those in Litomylus dis- 

 sentaneus, distinctly less than in L. scaphiciis, P3 with parastylid and 

 posterior cusps much better developed than in L. dissentaneous. Para- 

 conid on molars more reduced. Talonid basin a little less deeply 

 pocketed. 



Discussion. — A second jaw fragment with Mi and part of M2, 

 U.S.N.M. No. 21011, is also from the ledge locality and a single 

 lower molar of this small species was encountered at the saddle but 

 no material was obtained from the west end of the basin. 



Litomylus scaphiscus resembles the larger L. scaphicus in the more 

 reduced paraconids of the lower molars but is strikingly close in size 

 of both premolars and molars to L. dissentaneus. It differs from 

 L. dissentaneus essentially in the better development of the cusps of 

 Ps, the weaker paraconids of the molars (particularly Mj), and the 

 less deeply basined molar talonids. Moreover, the depth of the pocket 

 is greatest nearer the lingual margin than in L. dissentaneus. 



MEASUREMENTS IN MILLIMETERS OF TEETH IN TYPE SPECIMENS OF 



TWO NEW SPECIES OF IMomylus 



L. scaphicus L. scaphiscus 



U.S.N.M. U.S.N.M. 



No. 21014 No. 21010 



(type) (type) 



Ps, anteroposterior diameter : greatest transverse 



diameter 3-7'-^'-(>5 



P4, anteroposterior diameter : greatest transverse 



diameter 3-8 * : — 



^* Skaphiskos, from Greek skaphos (diminutive form) := hollowed out as a 

 basin, in allusion to the Bison basin. 



