246 



PEOFESSOK OWEX OX THE FOSSIL MAMMALS OF ATISTEALIA. 



seems to be a slight interruption in the course of the enamel at the middle of the fore 

 part of the tooth, which I have noticed in some of the smaller Wombats. The enamel 

 was coated by cement in the fossil. 



The succeeding molars slightly decrease in breadth of grinding-surface from the third 

 (m i), the decrease being most marked in the hind lobe of the last molar. This character 

 is more marked in Phascolomys lafifrons than in Phase, platyrliinus. The longitudinal 

 extent of the series of five teeth in Phascolomys medius is 2 inches 6 lines, as against 

 2 inches 1 line in Phase, platyrhimis, and 1 inch 8 lines in Phase, latifrons. 



The lower incisors of Phascolomys medius resemble in relative size those in Phasco- 

 lomys latifrons, in which they are smaller than in the bare-nosed Wombats ; but the 

 shape of the transverse section in Phase, medius is different (Plate XXXIV. fig. 4, i) ; 

 it gives a full ellipse, 4^ by 3|- lines, with the long axis almost vertical, but obliquely 

 inclined from above downward and rather inward. The enamel is thin, and limited to 

 the lower half of the long procumbent tooth. They are smaller, especially narrower 

 transversely, than the upper pair, and in this respect resemble the lower incisors of the 

 hairy-nosed, not the bare-nosed. Wombats. 



From the proportions which the extent of the molar series bears to the length of the 

 entire mandible in existing Wombats, I estimate that the lower jaw in the present 

 extinct species must have been between 6 and 7 inches in length. 



§ 2. Phascolomys magnus, Ow. — This species is founded on two portions of the upper 

 jaw, one containing the entire molar series of both sides (Plate XXXV. figs. 1-4), the 

 other retaining the second, third, and fourth molars of the right side. Both are from the 

 freshwater deposits of Queensland. The less fragmentary specimen includes rather 

 more than an inch of the diastema in advance of the molars, so much of the outer 

 wall of both maxillaries as includes the malar process, and a small portion of the 

 premaxillaries. 



The extent of each molar series is 3 inches 0 lines ; they run almost parallel with a 

 slight curve convex outward : the least interspace between the right and left series, viz. 

 at the fore part of the second molar [d <), is 1 inch ; the greatest, viz. at the hind part of 

 the last molar [m a), is 1 inch G lines ; the interspace between the right and left ante- 

 rior teeth {d 3} is 1 inch 2^ lines. 



Thus, as in Phascolomys medius, the disposition of the upper molars and general form 

 of the intervening palate is after tlic type of the existing hairy-nosed Wombat ; but 

 the concavity, transversely, of the palate is even greater than in Phascolomys medius^ 

 and becomes still more marked at the diastemal region. 



Tlie malar process of the maxillary (Plate XXXV. fig. 2, 21') rises at the same elevation 

 above the socket of the third molar as in Phascolomys medius, showing a variety amongst 

 the larger extinct Wombats which has been noted in the smaller existing spccicsf . 



Tlic prczygomatic ridge (ib. m) resembles, in its curved course, length, and narrow- 

 ness, that in Phaseulomys lafifrons. The maxillary anterior tluu-eto ad\anccs and bends 

 t I'liilosophical Transactions, 1872, p. 179, figs. 5 & G. 



