24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



citation, in which it is indicated tliat Entomolestes is only lower 

 Eocene in age. This should have included middle Eocene as well, 

 which is the age of the type species. 



PANTOLESTIDAE 

 AMARAMNIS,2=i new genus 



Type. — Amaramnis gregoryi, new species. 



Generic characters. — Resembling Palaeosinopa but lower molars 

 much more slender, and anteroposteriorly elongate trigonids of Mg 

 and M3 exhibit more acute anteroexternal angle between paraconid 

 and anterior crest from protoconid. Paraconid more closely joined 

 to metaconid. Talonid basin shallower, cusps less elevated and an- 

 terior crest from hypoconid less oblique. 



AMARAMNIS GREGORYI.s new species 

 (Plate I, figure 2) 



Type.—Leit ramus of mandible with M2-M3, Y.P.M. No. 14702. 



Horizon and locality. — Lowest beds of Knight member, Gray 

 Bull (Sand Coulee) equivalent, i^ miles south of Bitter Creek 

 Station, Sweetwater County, Wyo. 



Specific characters. — Size near Gray Bull Palaeosinopa lutreola 

 Matthew. Specific characters not otherwise distinguished from those 

 cited for the genus. 



Description. — Amaramnis gregoryi is represented only by the type 

 lower jaw, but the peculiarities of the two preserved lower molars 

 readily distinguish it. Although the molars are about the length of 

 those in the type (A.M. No. 15 100) of Palaeosinopa lutreola, their 

 width is very much less. Perhaps the most noticeable feature of the 

 teeth is the decidedly pentacodontine character of the trigonid por- 

 tion. The anteroposteriorly elongate trigonid shows a very sharp 

 flexure of the paraconid from the anterior crest of the protoconid, 

 much as in Pentacodon and Coriphagus, more acute than in Palaeo- 

 sinopa. The cusp arrangement of the talonid, however, more closely 

 resembles that of Palaeosinopa and Pantolestes with the prominently 

 developed hypoconulid. The basin of the talonid is relatively shal- 

 lower than in the forms examined, and the crista obliqua is directed 

 more forward, somewhat as in Pantolestes, quite unlike Pentacodon 

 and Coriphagus. M3 is not reduced as in Pentacodon and Coriphagus 



2a From Latin, amarus, a, bitter, and aimns, small river or stream ; with refer- 

 ence to Bitter Creek. 



3 Named for Dr. Joseph T. Gregory who graciously permitted me to study the 

 Marsh Bitter Creek collection. 



