SINCLAIR I 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 Halfnarhiphus 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 JVL, becoming much shal- 
lower anterior to the masseteric fossa, which is perforated, as in Ccenolestes , 
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 Caenolestidse, 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. 
Appendictilar 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 (PL 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. 1 1 ) 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. 
