PROFESSOR OWEN ON MACROPUS. 421 



The mastoid shows externally a narrow roughish vertical tract (PI. LXXIV fig. 1, 8 ) 

 between the exoccipital ( 2 ) and post-tympanic base of the squamosal ( 27" ), which forms 

 the lateral border of the occipital plane (ib. fig. 4, 27), but not so broad a one as in Fhas- 

 colomys (Trans. Zool. Soc. vol. viii. pi. 50. figs. 2, 3, 4, 6, 7, 27). The upper end of the 

 mastoid has a persistent round venous aperture behind the masto-parietal fissure 

 (Pi. LXXIV. fig. 1, If). In front of that fissure is the suprazygomatic venous foramen 

 (ib. fig. 1, m). 



Each parietal (ib. fig. 2, 7) extends forward in a pomted form into a corresponding 

 notch of the frontal, the apex ending at the usual place of a postorbital process (ib. 

 fig. 2, 12), which is rarely developed in the Kangaroos, and is never large. 



The presphenoid (ib. fig. 3, 9) extends forward to coalesce with the "septum narium;" 

 its hind portion contributes to the optico-prelacerate foramen ; its fore part supports 

 the small orbito-sphenoid which completes that foramen, overarching it to join the 

 alisphenoid, 6. 



The interfrontal suture (ib. fig. 2, 11) is persistent ; even very old males of Macropus 

 major show a trace of it. Each frontal begins behind, narrow or pointed, expands as it 

 advances, and bends down more or less abruptly to form the inner wall of the orbit, 

 where it unites with the orbito-sphenoid (10), palatine (ib. fig. 1, 201), maxillary (2Uj-), 

 and lacrymal (73) ; anteriorly the broad end or base of the frontal joins that of the nasal 

 (15), and is wedged between the nasal (fig. 1, is) and facial plate (21) of the maxillary. 

 The frontals contribute a small share to the anterior walls of the cranial cavity ; their 

 chief expansion is subservient to the development of the large and complex sinuses in 

 connexion with the olfactory cavity. This expansion is such in Macropus antilopinus, 

 Gd., as to have suggested for it the subgeneric term Osphranter^ ; it is somewhat less 

 developed in the present nearly allied species. 



The vomer forms the basis of the " septum narium," and speedily coalesces with the 

 plates which the prefrontals (14) contribute thereto. 



The nasals (ib. figs. 1 & 2, 15) are long and narrow ; their bases, less expanded than 

 in most other Marsupials, are subangular or rounded, and enter an emargination of the 

 frontals between the fronto-maxillary sutures ; the sides of the nasals articulate in two 

 thirds of their length with the maxillaries (21), in the remainder with the premaxillaries 

 (22), anterior to which the ends of the nasals are bevelled off' to points, freely over- 

 hanging the external bony nostril, but not extending so far forward as the dentai-y part 

 of the premaxillary. The external nostril (ib. fig. 5) is vertically oval, narrower than 

 deep ; the aspect of the aperture is forward and slightly upward. 



The upper turbinal sense-capsules (ib. fig. 5, is) coalescing with the compressed 

 centrum called "vomer," and with the neurapophyses called "prefrontals," compose 

 the bone which anthropotomy terms " ethmoid." 



The palatines, descending from the pre- and orbito-sphenoids, the ethmoid, and 



' Gr. viTcjiparTrjptos, sharp-smelling. 



