411 



penultimate and last molars of Macropus Titan : this I now believe to have come from 

 a female of that species. 



The mandible of Macropus Titan (Plate LXXXVI. figs. 11 & 12), after solution of the 

 soft parts in its original burial-place, shows the effect of the disturbance of the grave by 

 the dislocation of the rami, which had been somewhat loosely attached during life by the 

 partial syndesmosis of the symphysis. So separated and shifted, the right ramus being 

 pushed about 2 inches in advance of the left, the parts have rested without further 

 disturbance long enough to permit the dislocated rami to become connected together by 

 the petrified matrix. The bone, which during the same period had undergone some 

 degree of petrifaction, appears again to have been subject to movements of the matrix, 

 resulting in the amount of fracture of the most prominent parts which is common in 

 the fossils from the freshwater beds of the Australian localities yielding the subjects of 

 the present paper. But the later disturbances have not affected the artificial union of 

 the previously separated and dislocated rami. 



The jaw-bone in this specimen exceeds in depth and a little in length that of the 

 Macropus Titan in the Oxford Museum (Plate LXXXII. figs. 13, 15), but the longitudinal 

 extent of the four molars is the same. The present fossil is from an older individual : 

 d 4 is worn down to its base, and the ridges of m a (both of the lobes and links) show 

 more abrasion. The vertically oblong pit toward the inner side of the back part of the 

 last molar (ib. fig. 15) is well marked. The symphysial articular surface (ib. fig. 12) is 

 neatly defined behind ; its rougher part subsides anteriorly, and ceases about an inch 

 from the outlet of the incisive socket. The vertical diameter of this socket is 8 lines ; 

 that of the base of the incisor, where the tooth has been broken off, is 7 lines. 



The portion of a left mandibular ramus of a fine old male of Macropus Titan (Plate 

 LXXXVI. fig. 13) shows the largest size of the lower jaw which I have as yet seen in fossils 

 of this species. But though the depth of the mandible at the interval between d i and 

 m i is nearly half an inch greater than in the subject of fig. 11, or in the Oxford speci- 

 men (Plate LXXXII. figs. 1 3, 15), the teeth are not much larger. A figure of the working- 

 surface of the last molar in this large Macropus Titan is given in fig. 14, and one 

 of the hind surface of the same tooth in fig. 15, to exemplify the characteristic pit there 

 in the fossil. 



In the hind part of a mandibular ramus of a fine old Macropus Titan, with the last 

 molar well worn, and now much in advance of the coronoid process, the depth of the 

 jaw behind this tooth is 1 inch 6 lines, and the same at the interval between m 2 and 

 the debris of the socket of mi*. 



§ 3. Macropus affinis, Ow. — In a small collection of Marsupial fossils made by Sir 

 Thomas Mitchell, C.B., in a survey undertaken after his return to Australia in 1839, 

 and which he was so good as to transmit to the Koyal College of Surgeons, there were 

 confirmatory evidences of the two large species represented by the fossils of his first 



* This is the specimen alluded to as having been received, since the present paper was prepared, in the last 

 collection of fossils from the freshwater deposits of Queensland, transmitted by George Bennett, M.D., F.L.S. 



