33 



No teeth in the 1904 collection are recognized as belonging to this species. Matthew 

 (1902) is of the opinion that the two worn upper molars from Bone coulee, described by Cope, 

 under the above name, are probably not referable to the genus Hypertragulus. 



Mesohippus WESTON i, (Cope.) 



Plate III, figs. 10, 11, 12 and 13. 



Anchitherium, sp. indet,, Cope, 1885. The White River beds of Swift-current river, North 

 West Territory ; A.merican Naturalist, vol. XIX, p. 163. 



Anchitherium icestonii, Cope, 1 889. The Vertebrata of the Swift-current river, II ; idem, vol. 

 XXIII, p. 153 



Anchitherium westonii, Cope, 1891. The species from the Oligocene or Lower Miocene beds 

 of the Cypress hills ; Geol. Survey of Canada, Contr. to Can. Palseont., vol. Ill (quarto), 

 pt. I, p. 20, pi. XIV, figs. 1, 2 and 2a. 



Mesohippus westoni, Oshorn, 1904. New Oligocene horses; Bulletin Amer. Mus. Nat. Hist., 

 vol XX, p. 169. 



Mesohippus westoni, Lambe, 1905. On the tooth-structure of Mesohippus westoni (Cope) ; 

 American Geologist, vol. XXXV, p. 243, pi. XIV. 



Mesohippus westoni, Lambe, 1905. Fossil horses of the Oligocene of the Cypress hills, Assini- 

 boia ; Trans. Royal Soc. of Canada, second series, vol. XI, section IV, p. 44, pi. II, 

 figs. 1, la, lb, and lc. 



The type material of this species, from Bone coulee, Cypress hills, consisting of a right 

 upper molar, and two right lower molars in place in a fragment of the mandible, is in the 

 Museum of the Geological Survey at Ottawa. 



A right upper molar belonging to the collection of 1904, has been referred by the writer 

 to this species. The upper molar described by Cope is imperfect, the outer slope of the 

 ectoloph is missing and the anterior part of the tooth, including the protoloph, is much 

 damaged. 



The crown of the molar obtained in the summer of 1904 is practically perfect and had 

 been subjected to little use during the life of the animal ; it is most probably the second 

 molar and is shown in figures 10-13 of plate III. This tooth is brachyodout, with -well 

 developed low cross crests (protoloph and metaloph). The crown, seen from be'ow, is 

 suboblong in outline, transversely broader in front than behind and relatively narrow in an 

 antero-posterior direction. The outer border (ectoloph) rises higher than the cross crests. 

 The latter are unequal in length, the protoloph being longer and better developed than the 

 metaloph. The intermediate cusps (protoconule and metaconule) are both well defined, 

 although the protoconule is larger than the metaconule, and more distinctly separated from 

 the protocone than is the metaconule from the hypocone. The protocone is slightly larger at 

 its base than the hypocone, but both have about the same height. There is no hypostyle. 

 The parastyle is large, and adds considerably to the crown's anterior transverse diameter. 

 The mesostyle and metastyle are distinct, and the ribs distinguishable, the anterior ribs 

 being the better defined of the two. The cingulum is well developed and passes from the 

 metastyle entirely round the inner side of the crown to the parastyle without interruption, 

 except for a short distance on the front inner slope of the protocone ; it connects in front 

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