31 



Leptomeryx mammifer, Matth.ew, 1902. The skull of Hypisodus, the smallest of the Artio- 

 dactyla, with a revisiou of the HypertragulidEe., Bulletin Amer. Mus. Nat. Hist., vol. 

 XVI, article XXIII, p. 313. 



Leptomeryx mammifer, Matthew, 1903. The fauna of the Titanotherium beds at Pipestone 

 Springs, Montana, Bulletin Amer. Mus. Nat. Hist,, vol. XIX, article VI, p. 224, figs. 16 

 and 17. 



Leptomeryx mammifer was founded on lower molars, from Bone coulee, by Cope, who, 

 at a later date, arbitrarily associated with them upper molars from the same locality. The 

 best preserved of these latter, the one figured in 1891, may be regarded as the cotype of the 

 species. There are in the collection of 1904 separate upper molars that agree closely in size 

 and form with the cotype, and are, therefore, regarded asbelonging to this species. An upper 

 fourth premolar, obtained in 1904, is also thought to be referable to L. mammifer. 



It has been pointed out by Matthew (1902) that one of the characters of L. mammifer 

 relied on by Cope as a distinguishing one, viz., the presence in the lower posterior molar of a 

 " peculiar column intercalated between the heel and the posterior internal column," is in 

 reality the small antero-internal cusp of the heel found in other species of the genus. 



No lower molars are recognized in the collection of 1904 as belonging to L. mammifer. 



Leptomrryx speciosus, sp. nov. 



Plate VIII, figs. 10-15. 



A species of Leptomeryx is represented by a large number of separate teeth, of which the 

 upper molars are much larger than the type of L. esulcatus, Cope, considerably larger than 

 those of L. evansi, but not reaching the size of those of L. mammifer. This species is 

 apparently distinct from any of these three species. 



In the upper molars the proportionate development of the mesostyle, the anterior (para- 

 style), and posterior (metastyle) styles, and the ribs of the external face are much the same as 

 in L. evansi. The styles are quite different from the gibbous styles of L. mammifer, as seen 

 in the cotype of that species. 



In the upper molars a moderately strong cingulu'm is generally present for a short distance 

 at the base of the anterior slope of the protocone, and, in a number of specimens there is a slight 

 indication, as well, of a cingulum on the posterior slope of the hypocone. In two fourth 

 premolars a cingulum is present for a short distance on both sides (anterior and posterior) of 

 the inner crescent. In a majority of the upper molars a median internal cusp is present, 

 smaller than that of the molars of L. evansi. 



The lower molars referred to this species, relying on their size principally for their asso 

 ciation here, agree in size and general shape with the mandibular teeth referred provisionally 

 to L. esulcatus by Matthew in 1908, (op. cit ,p. 222, fig. 15). The Cypress Hills lower molars 

 have a slight anterior and posterior cingulum in the majority of cases, and there is also in 

 most of the specimens a small median external cusp having about the same degree of develop- 

 ment as the median internal cusp of the upper molars. No mention is made by Matthew of 

 a cingulum, nor of a median internal cusp in the Pipestone Springs lower molars, which, how- 

 ever, in other respects, and as regards exact size, agree with the Cypress Hills specimens. 



