258 



parallel with the fore half of the front lobe of m*: an extent of 3 inches 3 lines is 

 preserved of the origin of the pier as it passes forward and upward, where the fracture of 

 the maxillary traverses the interval between the sockets of d 3 and d i. The bony palate 

 arches upward and inward from the inner walls of the sockets of m i andra 2, in as great a 

 degree as from those of the socket of d 4. The extent preserved, in a straight line from 

 the outlets of the alveoli, is 2 inches. The palato-maxillary suture begins at the inner 

 or mesial fractured surface of the bony palate opposite the hind lobe of m 1 ; near the 

 interval between m 1 and m 2 it extends outward and backward with an oblique curve to 

 near the inner side of the outlet of the socket of m 3. Its relative position to the molars 

 agrees with that of the palato-maxillary suture in Phascolomys latifrons ; in Macropus 

 rufus the suture begins, mesially, at the transverse parallel of the interval between m a 

 and m 3, at least in an example with those molars in place and use. 



The palatine bone, like the maxillary alveolar tract, has been broken at the part 

 behind m 2, the broad single posterior root of which is exposed. But at the fractured 

 surface of the palatine there occurs, just opposite or parallel with the back part of ma, 

 a small tract of the natural smooth unbroken surface of the palatine, indicating a poste- 

 rior palatal vacuity, on the parallel of m 3, as in Phascolomys. The thickness, vertically, of 

 the fore part of the bony palate here preserved is 1 inch, of the hind part half an inch. 



In the younger, probably female specimens, the same admeasurements give 6 lines and 

 2 lines. 



Contrasting the difference of size, shape, and relative position of so much of the max- 

 illary zygomatic process and bony palate as is preserved in the two specimens just 

 described, one is at first inclined to deem them to have come from different species of 

 Nototherium ; and three species of the genus are indicated by mandibular characters. 



But in reference to the progressively backward extension of the zygomatic process of 

 the maxillary, this may be coincident with the progressive growth of the alveoli of the 

 hinder molars, as these teeth come into use ; in like manner, as their crowns are pushed 

 down to the line of wear in the ratio of the abrasion of their wedge-shaped ridges, so 

 the alveoli will cling to and follow the roots, growing as they lengthen, and giving a 

 curve or concavity to the palatal surface not present or needed in the less worn condi- 

 tion of m 1, m 2, and m 3, in younger individuals. 



With the foregoing evidences of the cranial characters of Nototherium we may safely 

 proceed to bring them out, or add to their saliency, by comparison with those in other 

 extinct and in existing Marsupialia. 



The skull of Nototherium is shorter in proportion to its breadth and depth than in 

 Diprotodon, and differs in the singular way in which the maxillary or facial part is bent 

 up upon the cranial part, exemplified in figure 1, Plate XXXVI., and by the angle, 

 before noted, which the bony palate forms with the basis cranii. The shortness is mainlv 

 due to that of the antorbital extent of the skull ; the diastema between the incisors and 

 molars is relatively as well as absolutely less than in Biprotodon. The Xotothere resembles 

 the Koala (ib. fig. 3) and Wombat in the small proportion of the skull in advance of 



