388 PROF. OWEN ON THE OSTEOLOGY 
diameter of the osseous cavity of the nose. Neither in Hypsiprymnus nor Macropus do 
I find the incisive palatal foramina entirely in the intermaxillary bones, as described by 
the author of the text in Pander and D’Alton’s ‘ Skeleti der Beutelthiere’ ; a small pro- 
portion of their bony circumference is due to the anterior extremity of the palatal process 
of the maxillaries ; and the same structure obtains in the Wombat, Koala, and Opossums. 
In the Dasyures and Phalangers a greater proportion of the posterior boundary of these 
foramina is formed by the maxillaries ; in the Petaurists they are entirely surrounded by 
the maxillaries, while in the Perameles the incisive foramina are wholly surrounded by 
the intermaxillary bones. ‘They always present the form of two longitudinal fissures. 
The maxillary bones in the Wombat send up a long, narrow, irregular nasal process, 
which joins the frontal and nasal bones, separating them from the intermaxillaries ; the 
part which projects into the temporal fossa, behind the orbit, presents two or three 
smooth tuberosities, formed by the thin plate of bone covering the pulps of the large 
curved posterior grinders. The corresponding part in the Perameles lagotis is perforated 
by numerous minute apertures, like a cribriform plate ; and this structure is presented 
in a slighter degree in the Potoroo and Ursine Dasyure. The antorbital foramen does not 
present any marked variety of size, which is generally moderate. It is much closer to 
the orbit in the carnivorous Marsupiata than in the corresponding placental quadrupeds. 
It is relatively largest in the Ursine Dasyure. It presents the form of a vertical-oblique 
fissure in the Wombat. Ihave observed it double in the Kangaroo. The chief diffe- 
rences in the maxillary bones, independently of the teeth and their alveoli, are presented 
by the palatal processes, the modifications of which I shall consider in conjunction with 
those presented by the palatal processes of the palatal bones. 
The perforations of the bony palate deserve particular attention ; they are generally 
specific, and of consequence in the determination both of recent and fossil species. 
In Phalangista Cookit', some of the Petaurists* and the great Kangaroo (Macropus 
Major), the bony palate is of great extent, and presents a smooth surface, concave in 
every direction towards the mouth ; this is pierced by two small posterior palatine fora- 
mina, situated at the anterior external angles of the palatine bones, close to the trans- 
verse palato-maxillary sutures : behind these foramina in the Kangaroo, and pierced in 
the suture itself in some Petaurists, are a few small irregular perforations. The bony 
palate is also entire in the Hypsiprymnus ursinus. 
In Macropus Bennettii’ there are four orifices at the posterior part of the bony palate : 
the two anterior ones are situated upon the palato-maxillary suture, of an ovate form, 
with the small end forwards ; the two posterior foramina are of a less regular form, and 
smaller size. 
In the Brush Kangaroo (Macropus Brunii, Cuv.) the posterior palatal foramina present 
the form of two large oval fissures, placed obliquely, and converging posteriorly. They 
1 Pl. LXXI. fig. 2. * Ib. fig. 3. 3 [b. fig. 5. 
