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vliich is well niarked in the Wombat, Myrmecobius, Petaurists, 

 Phalangers, Opossums, and Dasyures. In the Potoroos the ante- 

 rior extremities of the nasal bones coDverge to a point which projects 

 beyond the intermaxillaries. In some Petaurists and the Perameles 

 the corresponding points reach as far as the intermaxillaries ; and ia 

 Perameles lagotis the bony case of the nasal passages is further in- 

 creased by the presence of two small rostrai bones, resulting, as in 

 the Hog, from ossification of the nasal cartilage. 



" The intermaxillary bones always contain teeth, and the ratio of 

 their development corresponds with the bnlk of the dental ap- 

 paratus which they support. They are consequently largest in the 

 Wombat, \vhere they extend far upon the side of the face, and are 

 articulated to a considerable proportion of the nasal bones, but do 

 not, as in the placentai Rodentia, reach the frontai, or divide the 

 maxillary bone from the nasal. They present the next degree of 

 inferior development in the Koala, and both in this species and in 

 the Wombat bulge outwards, and thus remarkably increase the 

 transverse diameter of the osseous cavity of the nose. 



" Neither in Hypsipryninus nor Macropus do I find the incisive pala- 

 tai foramina entirely in the intermaxillary bones, as described by the 

 author of the text in Pander and d' Alton's ' Skelete der Beutelthiere,' 

 a small proportion of their buay circumference is due to the ante- 

 rior extremity of the palatai process of the maxillaries, and the 

 šame structure obtains in the Wombat, Koala, and Opossums. 

 In tlie Dasyiiri 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 ; ^rhile 

 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 \vhich joins the frontai and nasal bones, 

 separating them from the intermaxillaries ; the part which pro- 

 jects into the temporal fossa behind the orbit presents two or 

 three smooth tuberosities, formed by the thin plate of bone co- 

 vering the pulps of the large curved posterior grinders. The 

 corresponding part in Perameles lagotis is perforated by nume- 

 rous minute apertures likę a cribriform plate, and this structure 

 is presented in a slighter degree in the Potoroos and Ursine Da- 

 syure. The ant-orbital foramen does not present any marked va- 

 riety of size, which is generally moderate. It is much closer to 

 the orbit in the carnivorous Marsupiata than in the corresponding 

 placentai quadrupeds. It is relatively largest in the Ursine Dasyure, 

 and presents the form of a nearly vertical fissure in the Wombat. I 

 have observed it double in the Kangaroo. The chief difFerences in 

 the maxillary bones, independently of the teeth and their alveoli, 

 are presented by the palatai processes ; the modifications of which 

 I shall consider in conjunction •vvith those presented by the palatai 

 processes of the palatai bones. The perforations of the bony palate 

 deserv'e particular attention; they are generally specific, and of 



