420 ' THE PUERCO EroOH. 



This animal is a little larger than the Anisonckus sectoriits, and about 

 equal in the size of its skull to the gray fox. 



Haploconus xiphodon Cope. 



Proceed. Ainer. Philos. Soc, IStftJ, p. 466. 

 Plato XXV e; figs. 5-6. 



This species is represented by a mandibular ramus and perhaps by three 

 rami. The one on which the species rests contains five molars, the middle 

 cue of the series broken, so that its form cannot be positively ascertained. 

 It is probable that it is the first true molar, so that the animal exhibits the 

 last true molar not entirely protruded, and is therefore nearly adult. But 

 there are some reasons for suspecting the animal to be young. Thus the 

 last inferior molar does not exhibit more of a heel than the second u.sually 

 does, and the supposed third jjremolar is smaller than that tooth is in the 

 other species, having nearly the proportions of the second premolar. The 

 teeth present may then be supposed to be the molars from the second to the 

 sixth inclusive. But opposed to this view is the fact that the supposed third 

 premolar has more the structure of that tootli in details tlian that of the 

 second, and the specimens accompanying, which have the temporary den- 

 tition apparently of the same species, present premolar teeth of a very 

 different character. In any case the present specimen represents a third 

 species of the genus, and I describe it at present as an adult. 



The third premolar has a simple, compressed crown, about as high as 

 the length of its base, and without anterior basal tubercle. It has a narrow 

 triangular posterior face which is concave, and truncated by a cingiilum 

 below; no heel proper, nor lateral cingula. The fourth premolar is an 

 elongate tooth consisting of a compressed principal median lobe, an anterior 

 loVje connate with it, and a heel. The latter has elevated posterior and 

 interior borders. A rudiment of an exterior border is seen in a narrow 

 ridge on the external side of the posterior face of the principal lobe of the 

 tooth. The sides of the premolars present rather distant ridges, as in 

 Periptychus carinidens. The second true molar has two anterior and three 

 posterior tubercles; the latter close together, pointed, and of about equal 

 size. Of the anterior tubercles the external is much the larger and more 

 elevated. It is compressed, and has a curved subacute anterior edge, which 



