308 DAVIDSON BLACK 



what similar condition obtains, though in these animals the loop- 

 formation i.s much less extensive. In other ungulates, however, 

 the two crura of the ansiform lobule and the intercrural sulcus 

 can rarely be distinguished. 



Bolk (1. c.) has pointed out that the ansiform lobule consti- 

 tutes an unpaired center for the elaboration of tonic, sthenic and 

 static impulses for the musculature of the homolateral limbs and 

 in consequence is most highly developed in those forms in which 

 the power of independent limb action has been most perfectly 

 acquired. For this reason the lobule in question is more typi- 

 cally developed in carnivores than in ungulates. 



In the latter group, the functional reduction of the limb ele- 

 ments has progressed to the smallest extent in suillines; and in 

 hus, where both forearm and leg elements are retained as com- 

 plete and distinct bones, the ansiform lobule is relatively large 

 and characteristically loop-shaped. Among the ungulates, 

 though exceptions occur as noted above, it is evident that a 

 correlation does exist between the development of this lobule and 

 the functional development of the limbs. On this account it is 

 •of interest to recall that in Oreodon the bones of the forearm 

 and leg were complete and separate and further that it is probable 

 that a clavicle was also present (v. Scott, 1. c). 



With regard, therefore, to the characters of its ansiform lobule, 

 Oreodon apparently presents resemblances to both suillines and 

 certain ruminants. 



Lobulus parainedianus. In Oreodon this subdivision of the 

 posterior cerebellar lobe is overlapped dorsolaterally by the ansi- 

 form lobule so that it comes to lie at the bottom of a depressed 

 area between the latter lobule and the lobulus medianus posterior. 



Formatio vermicularis. This region of the cerebellum is well 

 developed in Oreodon and is arranged on a plan essentially simi- 

 lar to that obtaining among ruminants (e. g., Ovis, Cervus). At 

 the caudal end of the pars tonsillaris the ascending crus is appar- 

 ently in continuity with the paramedian lobule while rostrally 

 this crus abuts upon the lateral border of the lobulus simplex 

 and lobus anterior. Here it turns upon itself to become con- 

 tinuous with the crus descendens from which it is separated by 



