SINCLAIR: MARSUPIALIA OF THE SANTA 'CRUZ BEDS. 423 



ated by the wear to which the teeth have been subjected. An external 

 cingulum is present, as in Halmarhiphus and Ccenolestes. 



Mandible (PI. LXIII, figs. 8, 8a). In shape the mandible resembles 

 that of Ccenolestes, but is deeper in proportion to its length. The anterior 

 border of the coronoid is straight, without the convex curvature seen in the 

 latter genus (cf. PI. LXIII, fig. 14), and slopes obliquely backward. The 

 horizontal ramus is deepest beneath MT and MY, becoming much shal- 

 lower anterior to the masseteric fossa, which is perforated, as in C&tio/esfes, 

 by a small foramen situated near its inferior border. The angle is 

 strongly inflected. The condyle, which is placed far above the level of 

 the dental series, is flat transversely, convex antero-posteriorly, and con- 

 siderably wider internally than externally. The symphysial union of the 

 jaws was ligamentous, as in all known members of the Caenolestidae, the 

 symphysial impression extending as far back as the posterior premolar. 

 Two mental foramina are present, a large one beneath the posterior pre- 

 molar and a smaller foramen beneath the first molar. 



Appendicular Skeleton (PI. LXIII, figs. 10-13). Compared with the 

 size of the mandible, the bones of the fore limb are remarkably short and 

 slender, none of them exceeding the jaw in length. 



The neck of the scapula (PI. LXIII, fig. 10) is short and moderately 

 constricted. The glenoid cavity is slightly oval in outline and rather 

 shallow. The coracoid process is prominent, but incomplete at the tip. 



The humeral shaft is strongly curved antero-posteriorly and greatly ex- 

 panded distally. The head is strongly convex in all diameters and pro- 

 jects considerably beyond the shaft posteriorly. The greater tuberosity is 

 low, not extending above the level of the head. The lesser tuberosity 

 has been broken off. The deltoid crest is very prominent, forming a 

 broad flattened area which extends half way down the shaft. The distal end 

 of the humerus (PI. LXIII, fig. 11) is broad, owing to the great develop- 

 ment of the inner epicondyle and supinator ridge. The proximal end of 

 the latter is without hook-shaped termination. The inner epicondyle 

 has been broken off and is restored in outline in the figure. An entepi- 

 condylar foramen is present. 



The radius (PI. LXIII, fig. 12) is exceedingly slender. The head is oval 

 and capable of some degree of pronation and supination. Distally, the 

 shaft is slightly expanded and triangular in cross-section. The distal 

 epiphysis has been lost. 



