302 DAVIDSON BLACK 



oyrus. Caudally it does not extend below the level of the con- 

 fluens sinuum and rostrally it reaches to within a short distance 

 of the corono-ansate sulcus, but in no instance joins the latter. 

 In the relations and morphology of its lateral sulcus, Oreodon 

 thus conforms to a generalized and primitive ungulate type. 



Corono-ansate complex. The coronal sulcus forms a deep, well 

 marked furrow which reaches almost to the frontal pole of the 

 cerebrum and in every specimen the gyrus on its medial side is 

 high and prominent. Caudally the coronal is continuous with 

 an obliquely placed ansate sulcus whose mesial end is closely 

 associated with the margin of the hemisphere and probably cut 

 the latter, as frequently happens among modern artiodactyls (e. g., 

 Ovis and Bos). 



The corono-ansate complex may be independent of the supra- 

 sylvian (cf. figs. 3 and 23), but is usually joined to the latter 

 sulcus (in nine of the ten hemispheres examined). The junction 

 of the coronal and suprasylvian sulci in this manner is a condi- 

 tion which characteristically obtains in many modern ruminants. 

 Among suillines, on the other hand, such a condition but rarely 

 occurs and the coronal sulcus is usually joined with the upturned 

 intercalary, a feature which serves to distinguish the members of 

 this group from other artiodactyls. It emerges, therefore, that 

 the relations of the corono-ansate complex in Oreodon are of a 

 predominantly ruminant character. 



Suprasylvian sulcus. The suprasylvian sulcus extends from 

 the caudal pole of the hemisphere to the level of the ansate sulcus 

 in the form of a wide arch. Its caudal extremity shows a ten- 

 dency, towards bifurcation and the development of a short cau- 

 dally directed limb. The latter in my preliminary report was 

 spoken of as a possible homologue of the ramus suprasylvii poste- 

 rior of Sus, since though small, its relations are identical with 

 the more constantly developed sulcus bearing this name in 

 modern suillines (cf. Holl, 1. c). 



Rostral of the level of the processus acuminis ectosylvii, a 

 small laterally directed notch is frequently present on the supra- 

 sylvian sulcus which may correspond to the ramus anterior supra- 

 sylvia (Kappers, 19). This sulcus has been termed by Holl the 



