422 PEOFESSOE OWEN ON MACEOPUS. 



frontal (at 20j-, fig. 1), internal to the hind part and entorbital plate of the maxillaries 

 ( 2U'), bend inwards at right angles to unite together at the bony palate (ib. fig. 3, 20), of 

 which they form the hind portion from the penultimate molars backwards. From the 

 sockets of these and of the last molars the palatal plates of the palatines are separated 

 by a narrow strip of the maxillaries (ib. 21" ), behind which the palatines ( 20" ) extend 

 and expand to join the pterygoids (24). 



The hind border of the bony palate is feebly concave. The postpalatal apertures 

 pierce the outer angles of the palato-maxillary sutures ; they are small oval foramina in 

 some (usually the larger) species of Kangaroo (as at b, fig. 3), but extend into both 

 bones to form wide vacuities in other species \ the bony palate being one of the seats of 

 variety in the present family. The proper palatine plates may show one or more fora- 

 mina behind the normal postpalatal or maxillo-palatine vacuities. 



The orbital plate (ib. fig. 1, 20^:) of the palatine is pierced by the orbito-palatal 

 foramen, and is notched to contribute, behind, to the spheno-palatal foramen, and, in 

 front, to the palato-maxillary foramen. 



The maxillary is a large and complex bone. Articulating with the fore and outer 

 parts of the palatine, it develops the alveolar tract for the grinders, also the part of 

 the bony palate between the palatines and premaxillaries, and the main part of the 

 floor of the orbits, where it is pierced by the entorbital canal (e) and notched by the palato- 

 maxillary foramen {f). Then, these extending from the orbit forward, beneath, or 

 internal to the lacrymal and malar bones, the maxillary forms the side wall of the face 

 (fig. 1, 21) as far forward as the premaxillary (ib. 22). This facial wall of the maxillary 

 is sinuous, convex vertically at its upper part, concave at its lower part, the concavity 

 being deeper in the larger kinds of Kangaroo : it articulates behind with the frontal 

 (11), lacrymal (73), and malar (26), above with the nasal (15), in front with the premaxillary 

 (22). At the lower part of the maxillo-premaxillary suture the maxillary usually sends 

 forward a sharp narrow process to be wedged into the premaxillary, receiving into a 

 notch below a similar process from that bone. The suborbital canal divides into a dental 

 and an antorbital canal. The anterior outlet (ib. fig. 1, 21') of the antorbital canal, 

 usually vertically oval in shape, varies in its relative positions to the orbit in difierent 

 species of Kangaroo. A ridge near the maxillo-malar suture leads to the zygomatic pro- 

 cess, of which it forms the outer border. This process (21 x) is the seat of variety, as 

 to shape and size, in different species of Macropodidae. 



The premaxillai-ies unite by a rhomboid facial plate (ib. fig. 1, 22) with, usually, the 

 termmal third of the nasals (15) and with the maxillaries (21). They develop sockets 

 for three pairs of incisors {i 1, 2, 3), and form the anterior end of the bony palate, which 

 is pierced by the "incisive foramina" (ib. fig. 3, 22') in the form of oblong slits, closed 

 behind by the pointed ends of the palatal plates of the maxillaries. External to these 

 foramina the premaxillaries usually show a smaller foramen (ib. a!). 

 ' Trans. Zool. Soc. vol. ii. pi. 71. fig. 5 {Halmaturus bennettii). 



