206 



GREGORY: NOrilARCTUS, AN AMERICAN EOCENE PRIMATE 



ms has an abortive hypoconulid; nii is the largest of the series. In Myoxicebus the stout lower molars 

 rather suggest the Ada pis magnus type. 



In brief, with regard to the pattern of the lower molars, the Lemuridee are evidently more nearly 

 allied to the Adapinse than to the Notharctinse, the latter representing in most particulars an older type. 

 Special evidence of structural affinity with the Adapinse is revealed by the lower molars of Lepilemur 

 which are less degenerate than those of Lemur; analogies with Adapts magnus are shown in the lower 

 molars of Myoxicebus simus. 



Lower Jaw 

 Platf LII; Text Fig. 7() 



The evolution of the lower jaw of the Notharctinse has been traced in preceding pages. It will be 

 recalled that in the early forms of Pelycodus the mandible was fairly stout, with a robust horizontal ramus 

 which was gently curved below, bearing canines of moderate size and small semierect incisors; the angle 

 was produced backward into a long fairly strong apophysis, the symphysis remained open. In the latest 

 types, the symphysis coalesced in adults, the ramus was stout but rather shallow, the coronoid unusually 



2 



Fig. 76. Lower jaws of Xoihardu.'i and Lepilemur. Medial aspect. Natural size. 



1. Nothardus venticolus. Amer. Mus. No. 146.55. 



2. Lepilemur mustelinus. Amer. Mus. No. .31251. 



Fig. 77. Lower jaw of Adapis parisiensis. Medial aspect. After Stehlin. Natural size. 



large, high and very little recurved, the condyle strongly convex both anteroposteriorly and transversely, 

 the medial articular surface of the condyle being extended into a prominent apophysis directed downward 

 and backward. In the Adapinte, it will be recalled, the horizontal ramus becomes very stout with greatly 



