Marsh Collection^ Peabody Museum. 



349 



ably augmented in the region of the implantation of the single 

 enlarged incisor. The crown of this tooth is not preserved, 

 being broken away at the level of the alveolus. The root is 

 suboval in cross section, with a rounded angular part internal. 

 Projecting the contour of the broken part of the jaw from 

 that which is preserved, the horizontal ramus is seen to be 

 rather shallow and slender. There was a well-developed mas- 

 seteric fossa, the anterior portion of which is shown in the 

 specimen. That which may be regarded as the most extraor- 

 dinary feature of the jaw is the practical absence of cheek 

 teeth. The dentinal border is preserved entire and in this are 

 to be. seen two shallow sockets, the first of which is situated 

 immediately posterior to the enlarged incisor. After a short 

 interval behind, a second similar alveolus occurs, and it is per- 

 fectly evident that these served for the implantation of two 

 single-rooted styliform teeth, which were apparently caducous. 

 The remainder of the tooth border was entirely edentulous. 

 The mandibular symphysis is not rugose, and there is no trace 

 of any tendency to coossitication of the two rami. 



The characters of the bodies of the cer- 

 vical vertebrae are of an indifferent nature, 

 and furnish little or no information of 

 the affinities of the species. They are 

 rather broad and depressed, and are with- 

 out inferior keels, as in the rodents and 

 certain lemurs, notably Nycticehus. The 

 caudal vertebrae denote that there was a 

 long tail. The ribs, as indicated by a few 

 heads, are likewise of the usual pattern 

 and wholly uncharacteristic. 



The glenoid cavity of the scapula has a 

 form usually seen in the living lemurs, 

 perhaps more resembling that of Propi- 

 thecus than any of the other existing 

 species. It will, however, answer quite 

 as well for that of a squirrel. The 

 humerus, figure 108, is more characteris- 

 tic, and it is in this bone that the Primate 

 affinities begin to manifest themselves. 

 The head is globular, somewhat pointed 

 behind,, and overhangs the shaft but 

 slightly. The greater tuberosity rises to 

 the level of the head, and is of consider- 

 able fore and aft extent. It equals 

 slightly more than one-half the antero- 

 posterior diameter of the articular portion. The lesser tuber- 

 osity is also prominent and separated from the greater tuber- 



FiGURE 108.— Eight 



humerus of Metacheiro- 

 mys Marshi Wortman ; 

 front view ; natural size. 

 (Type.) 



