CREODONTA. 325 



M hrachjstomus. I therefore refer the two species first mentioned to Panfo- 

 lesfes and place that genus in the Artiodactyle sub-order. 



The species of 3Iioclcenus can be only as yet compared in their dentition. 

 The characters thus derived are the following: 



I. Second inferior true molar without auy intern.al cusp on the heel, but a low ridge. 

 Last true molars much smaller than the others; length of inferior true mohirs, 



.018 M. turgidus. 



Last true molars not reduced ; second superior, .015 by .013 ; largest . . M.ferox. 



Last true molars not reduced ; length of true molars, .012, least M. minimus. 



II. Second inferior true molar with internal posterior cusp. 



Last inferior molar reduced; inferior premolars robust; length of true molars, 

 .016 M. baUhcini. 



Last inferior molar not reduced; inferior true molars, .020; inferior premolars com- 

 pressed conic; superior true molars, .026 M. snhtrigonits. 



III. Second inferior true molar unknown. 



Larger ; second superior molar, .012 by .010 M. corrugatus. 



Large; lower true molars, .023, last little reduced ; second superior, .Oil by .008. 



M.'protogonioides. 

 Small ; superior true molars about .018 ; second larger than first, which is much larger 



than fourth premolar M. biicculentus. 



Large; cusps of inferior molars obtuse; inferior pm. iii, .008, its heel short and 



small M. mandibularis. 



MlOCL^NUS TURGIDUS Cope. 



American Natnralist, 1^81, p. H30, Sept. 22; Paleontol. Bull. No. 3^, p. 489, Sept. 30, 1881 ; Proceed. Amer. 



Pbilos. Soc, 1881, p. 489. 

 Pl.ate XXV e, figs. 19-20 ; LVII f, fi^s. 3-4. 



The remains of this species have been more frequently obtained than 

 those of others of the g-enus, eight individuals being represented in my col- 

 lection. The characters displayed by the typical specimen are as follows: 

 There are no cingula on the second, third, or fourth premolars. The last 

 two are wider than long, and the external face is a little flattened. The 

 tubercles in the third and fourth are conic; the external has a small one at 

 the anterior base and a rudiment at the posterior base, and there is a low 

 one on the posterior side at the middle. The second true molar is wider 

 than the first. The tubercles are all round in section. Besides those 

 already mentioned, there is a rudiment of a posterior inner on the first, 

 which is represented b}- a cingulum on the second. The latter has basal 

 cingula all around except on the inner side ; the same are visible on the first 

 true molar in a rudimental condition. Enamel nearly smooth. 



