26 



Measurements of type specimen. 



MM. 



Internal anteroposterior diameter .-. 9 • 00 



Anterior transverse diameter 8 00 



Height of protocone 4 70 



Height of hypocone 3 • 80 



Locality :- — Bone coulee, Cypress hills. Collection of 1904. 



Elotherium coarctatum, Cope. 



Plate II, tigs. 10-15, and plate III, figs. 1-6. 



This species, based on the greater part of a left mandibular ramus discovered by Mr. T. C . 

 "Weston in the Cypress Hills deposits during the summer of 1888, was first described by Pro- 

 fessor Cope in the American Naturalist, vol. XXIII, p. 628, July 1889, in his third article 

 on the '• Vertebrata of the Swift-current river." Cope's fuller description, with illustrations 

 of the type specimen, appeared in 1891 in part I of this volume. 



The original description of 1889 is worded as follows: — " Elotherium. coarctatum, sp. 

 nov. — Represented by a left mandibular ramus with condyle, which supports all of the molar 

 teeth. The species differs from the E. mortonii, with which it agrees nearly in size, in having 

 all the premolars in a series uninterrupted by diastemata, except a very short one between 

 pm. iii and iv.* The second premolar is the most elevated, and the third and fourth are 

 abruptly smaller. The fourth has one compressed grooved root. The molars are peculiar in 

 having the two anterior cusps elevated above the three posterior ones, as in Miockenus sp. 

 The posterior, or fifth tubercle, is well developed, especially on the m. iii." 



"Length from condyle to edge of canine alveolus, 295 mm.; do. to last molar, 125 ; do. 

 of true molar series, 67 ; do. of m.i, 22 ; width of do., 13 ; elevation of pm. ii, 21 ; length of 

 base of crown do., 28 ; depth of ramus at m.i, 55." 



An upper molar, obtained by Mr. Weston at the Cypress Hills localit\- in 1884, and 

 assigned to Elotherium mortoni, Leidy, by Cope in his earlier references** to the Survey 

 collections, was, in 1891, referred to E. coarctatum in his final description of the species. 



This upper tooth, plate II, fig. 10, is regarded as m 1 from the right side. It has six 

 low tubercles arranged in two rows transversely, of which the inner posterior tubercle 

 (hypocone) is apparently not separate from the cingulum. The two outer tubercles (paracone 

 and metacone) are well developed, the paracone being the larger of the two. Loth the inner 

 tubercles in this specimen are injured, but the protocone has been apparently of fair size. The 

 protoconule and metaconule are well marked but do not attain the height of the outer cones. 

 The cingulum is conspicuous on the anterior and posterior faces of the crown. The tooth has 

 three roots. 



Another right upper molar, fig. 11, belonging to the writer's collection of 1904, is referred 

 to this species. It is the posterior tooth of the series and is of about the same size as the 

 first upper right molar just mentioned. It resembles the last upper molar of E. mortoni, as 



* The usual premolar enumeration from front to back is here reversed. 



** American Naturalist, lSST), vol. XIX. The White River beds of Swift-current river, North West Territory, p. 163 

 (Entdodon mortoni, Leidy); and Geol. and Xat. Hist. Survey of Canada, 1885, vol. I, new series, appendix I, p, 84 C 

 (Elotherium mortoni, Leidy I. 



