240 REMARKS ON POST-TERTIARY PHASCOLOMYIDiE, 



The humerus is seen at a glance to be much stouter, but as the 

 condylar region of the more perfect specimen is wanting its rela- 

 tive proportions cannot be ascertained with precision. With an 

 approximate length of 124 mm., against 122 in platyrhinus, the 

 width of the shaft at its proximal third is 3 mm., its antero- 

 posterior thickness 2*5 mm. greater ; it is, therefore, 2*5 mm wider 

 than in a recent bone of the same length ; at the proximal end the 

 long diameter of the head and greater tuberosity is 2*5 mm., the 

 short diameter across the head only 0*8 mm. greater ; in this region 

 it is, therefore, relatively longer and of a different form. Although 

 the head is but little larger antero-posteriorly, it is produced 

 downwards upon the hinder surface of the shaft much more than 

 in platyrhinus, more even than in lati/rons, and with a still more 

 angular margin than in the latter species. The importance of 

 this exaggeration of one of the features peculiar to lati/rons should 

 be duly appreciated. The ectotuberosity, as to size, is in about 

 the same proportion to that of the head as in platyrhinus, but it is 

 smoother, more symmetrical in form, wants the triangular facet, 

 and descends lower on the shaft ; the extent of its base on the 

 thenal side is platyrhine rather than latifront. In the extension 

 of the transverse diameter of the proximal end of the shaft we see, 

 on the other hand, a second latifront character in excess. The 

 lesser tuberosity resembles that of platyrhinus but is not so 

 distinctly grooved off from the head, nor does it descend in a 

 pointed form on the entothenal edge. The teretotriceps ridge is 

 extremely short and in shape oval, very different both in form and 

 extent to that of either of the living species ; midway between it 

 and the head is a tuberiform ridglet, perhaps an outlier of the 

 other. The pectoral ridge is an elevated line descending con- 

 tinuously from the greater tuberosity, in other structural respects 

 most nearly resembling that of platyrhinus, but differing in position 

 as it marks off the inner third instead of the inner half of the shaft. 

 The prominence and retroflexion of the angle of the deltoid ridge 

 are intermediate in degree between those exhibited by platyrhinus 

 and lati/rons. The deltoid and pectoral ridges do not converge 

 distad, the surface between them is comparatively flat, and the 



