27 



described by Leidy in 1853 in "The Ancient Fauna of Nebraska," plate VIII, fig. 1, but the 

 six tubercles are more distinctly marked in the Cypress Hills tooth. The cingulum is con- 

 tinued round the entire crown, except for a short distance at the base of the inner slope of the 

 protocone ; it forms a broad shelf anteriorly, and is prominent posteriorly. Seen from above 

 the crown in outline is unequally four-sided : it is transversely much narrower behind than 

 in front. It is low with six conspicuous tubercles, of which the outer and inner anterior ones 

 (paracone and protocone), are about equal in size and larger than the others. Of the three 

 tubercles forming the transverse posterior row, the inner one (hypocone) is connected with 

 the cingulum. 



Two fragments of the lower jaw of this species were also obtained in 1904. These are 

 a part of the left ramus with molars i, ii, and iii, and a small portion of the right half of the 

 jaw holding the first molar. The teeth agree in all particulars with the corresponding ones 

 of the type specimen. 



Two teeth, the upper third and fourth premolars of the right side, collected in 1904, are, on 

 account of their large size, referred to E. coarctation with some hesitation. They were found 

 together, and probably belonged to the same individual. If they properly belong to this 

 species, and they are apparently not referable to any other described species from the 

 Oligocene, they will indicate that in E. coarctation the upper third and fourth premolars 

 are considerably stouter in every way than the corresponding teeth of the lower jaw. Of these 

 specimens, the third premolar, figs 12 and 13, is a simple robust cone, elongated antero- 

 posteriorly, and supported on two roots, of which the hinder one is the thicker but shorter 

 of the two. A cingulum passes round the base posteriorly and is present, but feebly developed, 

 anteriorly. The enamel is roughened by short vermicular markings, which, toward the base, 

 above the cingulum, pass into conspicuous wrinkles. The crown shows signs of wear toward 

 the inner side behind and along the front slope. The fourth premolar, figs. 14 and 15, is a very 

 strong, three-rooted tooth, with a transverse diameter greater than its maximum antero- 

 posterior diameter. The crown consists of an outer conical cusp with a smaller, less elevated 

 one on the inner side. A strong cingulum is present except at the centre of the base of the 

 external slope. This tooth is also considerably worn on the front and back slopes of the 

 crown, more particularly on the former. Except where worn the surface above the cingulum 

 presents the same style of surface marking observed in the third premolar. 



Measurements. 



MM. 



Upper right m. iii, plate II, fig. 11 : — 



Transverse diameter of crown, maximum , 22 



Anteroposterior " " 22 



Upper right m. i, plate II, fig. 10 : — 



Transverse diameter of crown , 21 



Antero -posterior :i • 20 ■ 5 



Upper right pm. iv, plate II, figs. 14 and 15 : — 



Transverse diameter of crown, at hase 29 



Antero-posterior " " " maximum. . 26 ■ 7 



Height of crown, external , 23 



Upper right pm. iii, plate II, figs. 12 and 13 : — 



Transverse diameter of crown at base, maximum 18 



Antero-posterior " " " 32 5 



Height of crown, external , . 27 



