PEOPBSSOE OWEN ON MACEOPUS. 425 



(fig. 6 : in this figure the grinding-siirface of d 4, pushed out of line in the lower 

 jaw, is added in front of the figure of the tooth so displaced). 



The first, perhaps chief, difference between Macropus rufus, Dsm., and M. major, 

 Shaw, is the smaller relative extent of the crown of the upper and outer incisor, 3 i \ 

 which shows only one shallow vertical impression along the middle of the outer 

 surface. On this mainly would rest its claim to a subgeneric distinction, such as 

 Gould has indicated by the term Osphranter ; but the incisor-character is not repeated 

 in other species of Osphranter (M. robustus, M. antilopinus, e. g.). The above dental 

 distinction of M. rufus, however, is associated with several cranial ones. In the 

 skull of a full-sized male, with teeth more worn than in that of a M. major com- 

 pared with it, the temporal ridges have not met along the sagittal suture, but 

 are separated by a tract half an inch in breadth, along the middle of which the 

 sagittal suture persists. The anterior angles of the parietals give better indications of 

 postorbital tubercles. These, however, are not more shown in M. rufus than in M. 

 major. In a skull of the 3L {Osphranter) robustus compared, which retains the 

 premolar (^3) with four fully developed molars behind, the sagittal crest is better 

 marked than in M. major and M. rufus, in which that premolar is shed. 



The Great Eed Kangaroo is one of the largest ^ of the tribe ; and the skull here 

 described equals in length that of the largest in the Table of Measurements of M. 

 major^, yet it indicates a less powerful animal. The paroccipitals are more slender. 

 The zygomatic arches have less span and depth ; the masseteric process is much 

 shorter ; the ridge above the fore part of its base is due to the malar more than to the 

 maxillary. The mandible is more slender; the coronoid process is shorter and 

 narrower from before backward ; the depth of the ramus behind the molar series is 

 notably less in 3L rufus ; yet the last molar, with the same fore-and-aft extent as in 

 M. major, is broader. 



The basioccipital ridge in M. rufus is sharper. The upper border of the foramen 

 magnum is notched. The condyles are narrower, and the ectocondylar grooves deeper 

 and wider. The superoccipital is less elevated and more truncate atop ; the base of 

 the occiput is narrower. The facial plate of the lacrymal is broader, and the lower 

 and larger foramen is more external. The antorbital foramen is further from the 

 orbit. The premolar part of the skull is shorter and deeper; the maxillary out- 

 swelling is less definite. The facial plate of the premaxillaiy is broader antero- 

 posteriorly. The incisive foramina are longer and further from the third incisors. 

 The postpalatal apertures are larger, especially the right one ; but this may be a 

 variety : the bony palate behind them shows more and larger irregular perforations, 

 the hamular process of the pterygoid is less defined, than in Macropus major. 



Such are the chief differences observable in the skulls of M. rufus and M. major ; and 

 they are here noted as guides in the comparison of fossil cranial parts of Macropodidse. 

 ' As indicated by Waterhouse, op. cit. p. 107, and illustrated in his plate v. fig. 3. - lb. p. 104. ^ lb. 



VOL. IX. — PART VIII. March, 1876 3 m 



