802 PROCEEDINGS OF THE ACADEMY OF [1892. 



which is cleft but a short distance below the apex ; the paracouid 

 is very small, depressed and submedian in position, i. e., standing in 

 front of the space between the ]n-oto- and metaconids. The talon 

 is basin-shaped and consists of hypo- and entoconids which may be 

 of nearly the same size (G. rusticus) or the former may be much 

 the larger ((x. levisanus). A minute hypoconulid is also present. 

 M* is much reduced. 



Three species: G. (Trusodon, 3Iioelcenus) levisanus Cope, G. 

 {Miocl(znus) gaudryanus Cope, and G. (Trusodon, Mioclcenus) 

 rusticus Cope. Puerco. 



MICROCL.a:NODON, gen. nov. 

 Syii. Aliocluiiiis Cope, m part. 



Known only from lower molars, which are much like those of 

 Gonincodo)), es])ecially in the constitution of the trigonid, but the 

 talon is very ditterent and agrees with that of Deltutherimn and 

 Pentacodon in the absence of the entoconid and large size of the 

 hypoconulid, especially in m^ ; tiie valley is thus widely open on the 

 inner side. 



One species: 3f. (^Tri'isodon, Mioclcenus) assurgens Cope. Puerco.' 



SARCOTHRAUSTESi Cope. 

 Syn. MiocLvmis Cope, in part. 



The largest Puerco Creodouts are to be found among the species 

 of this genus-. The superior molars, so far as they are known, and 

 the lower premolars agree closely with those of Goniacodon, the 

 only differences being their larger size, more massive cusps, thicker 

 and more prominent cinguluni, especially at the antero-external 

 angle of the crown. ^3 is oval in shape and I'educed in size, having 

 lost the metacone. The anterior lower premolars are remarkable for 

 their small size and simple construction, but jr* is very much larger 

 and higher and has a large talon, divided into inner and outer 

 cusps. The lower molars differ from those of Goniacodon in the 

 composition of the trigonid; the protoconid is much the largest 

 element, the para- and metaconids are greatly reduced and placed on 

 the same fore and aft line, as in Tri'isodon, but the talon is very 

 different, consisting of hypo- and entoconids and small hypoconulid, 

 which may or may not be much enlarged on m^^ the size of which 

 tooth is very variable in the different species. The skull has a 

 very small cranial cavity and a very high occipital crest, which is 



1 Proc. Am. Phil. Soc, 18S1, p. 193. 



