A NEW GENUS OF FOSSIL MASSUPIALS.— LONGMAN. 71 



The maxilla extends anteriorly on the Hoor of the palate for a distance 

 of 110 mm. beyond the premolars. The palate is here convex with a median 

 groove. The lateral sutures between the maxilla and the premaxilla cannot be 

 satisfactorily traced. 



Premaxilla. — Euryzygoma dunensc is relatively longer in the facial region 

 than is the cast of the cranium described by Maeleay. The gnathion is 187 mm. 

 from the anterior borders of the premolars. The diastema is 112 mm. In 

 section the premaxilla is subquadrate. Owing to fractures its union with the 

 nasals is missing on both sides. On its palatal surface it is concave in the 

 region between the two posterior incisors, where there are three small foramina. 

 The premaxilla is thickened anteriorly and its superior margin terminates in 

 a raised oval boss, which suggests an attachment for cartilage. At the alveoli 

 of the large first incisors the width is 74 nun., and the height is 101 mm. The 

 incisors have been lost, post mortem, but the dimensions and disposition of their 

 cavities give valuable evidence of their nature. The large anterior pair were 

 evidently strongly curved in their downward course, and were subcylindrical 

 and only slightly diverging. At the antero-inferior border the alveoli are 

 separated by a distance of 19 mm. A loose incisor, 23 X 29 in diameters, from 

 another specimen, fits fairly M'ell into either cavity. On the anterior surface of 

 the premaxilla there are extensive exposed alveolar surfaces. The alveolus of 

 the second incisor, which is contiguous with that of the first on the labial border, 

 is approximately 13 X H- The third incisor alveolus is placed on the labial 

 border about 15 mm. behind that of the second, to which it is subequal. It is 

 evident from its contours that the third incisors were obliciuely set and 

 procumbent in position. 



For purposes of description the premaxilla has been treated as a single 

 and not as a paired bone. 



Glenoid Fossa. — Although the postglenoid process is very incomplete, the 

 actual fossa is well preserved on the right-hand side. This is 102 mm. in length, 

 whilst the actual concavity, apart from its shelving anterior border, is 15 mm. 

 Some idea of the articular surface of the mandibular condyle may be gauged 

 from these dimensions. The plane of the fossa is set at an angle of 85° to the 

 median line of the cranium, the condyle thus being scarcely oblique in its setting. 

 Laterally the posterior extension of the jugal forms part of the shelving anterior 

 border of the fossa. 



Basal Bones. — The ba.sioccipital and basisphenoid have been greatly 

 fractured, about fifteen segments forming the contours which have been put 

 together. The combined bones slope upwards at an angle of 18° from the plane 

 of the bony palate, being 12° less than the angle noted by Owen for the cast of 



