1 8 8 2 .] Geology and Palceontology. 4 1 j 



denly descends. The inner side of the ramus is concave, while 

 the external side, anterior to the masseteric fossa is convex. 

 The incisive alveolus is thus thrown inside the line of the 

 molars in front. There is a large fossa exposed by weathering, 

 below and behind the last molar, which is identical with that seen 

 in Hypsiprymnus and Macropus, and indicates a large dental 

 foramen. Below the middle of the fourth premolar tooth, the 

 incisor tooth is quite large, suggesting whether it had not a per- 

 sistent growth, as in the rodentia. 



The posterior cusp of the fourth premolar is triangular in pro- 

 file, the anterior edge descending steeply. It is uncertain 

 whether the edge of the crown rises again, forming another lobe. 

 The apex of the cusp is conic. The first true molar is of large 

 size and remarkable form. The crown viewed from above is a 

 long oval. It has a deep median longitudinal groove, which 

 sends out branch grooves alternately, and at right angles to the 

 edge. The spaces between the grooves form block-shaped 

 tubercles, four on the inner and five on the outer sides, whose 

 transverse diameter generally exceeds their anteroposterior. The 

 median groove is open at its anterior extremity ; the posterior is 

 closed by an elevated convex margin. The apices of the lobes 

 are obtuse where not distinctly worn. The last (second) true 

 molar is much shorter, and a little wider than the first, and has 

 the same character of surface. There are two large tubercles on 

 the inner side, and four smaller on the external side. The 

 posterior end of the crown is narrower than the anterior. The 

 anterior base of the coronoid process is opposite the posterior 

 extremity of the first true molar tooth. The jaw with its denti- 

 tion, in its present condition, has a curious resemblance to that of 

 a tubercular-toothed Mtstodon, with the order of size of the 

 molars reversed. Length of base of fourth premolar .0108. Ver- 

 tical diameter of root of incisor .0070. Diameters M. I ; ante- 

 roposterior .0107, transverse .0050; diameters M. 11 ; anteroposte- 

 rior, .0060, transverse .0060 ; depth of ramus at front of P-m. iv, 

 •0120; depth of ramus at front of M. 1, .0190; depth of ramus 

 at posterior edge of M. 11, .0150. 



Found by D. Baldwin in the Puerco bed of Northwestern New 

 Mexico.-,?. D. Cope. 



Two New Genera of the Puerco Eocene.— Haploconus linca- 

 ws, gen. et sp. nov. — Char. gen. The same as Anisonchus, except- 

 ln g that the crown of the third superior premolar is a simple 

 cone, wanting the large crescentic crest of the inner side seen in 

 that genus and Catathlaus. It is more nearly allied to the two 

 genera named than to Phenacodus. Char, specif. These are de- 

 lved from a number of specimens, the species having been abun- 

 dant m New Mexico in the earliest epoch of the Tertiary. It is 

 a oout the size of the and differs from it in 



