400 



monly these several transverse elevations are connected together by ridges which affect 

 a longitudinal course : that which ties the prebasal ridge to the front lobe is the " fore 

 link " (Plate LXXX. fig. 29, & Plate LXXXI. fig. 13, ms, s), that which ties together 

 the main lobes is the " mid link " (r), that which descends to the " postbasal" ridge is 

 the "hind link " (£), of which ridge it frequently seems to be the sole representative 

 (Plate LXXXI. fig. 18, t). 



The upper molars are broader than the lower ones, and the prebasal ridge is narrower 

 (antero-postcriorly) ; but the ridge descending from the hinder and inner angle of the back 

 lobe to the base of the hind surface of that lobe (" hind link " and " postbasal ridge ") is 

 usually better marked or more commonly present in the upper than in the lower molars. 



The coronal modifications of these teeth are represented in certain existing species 

 in figs. 23 to 28, Plate LXXX. ; to these are added figures of a lower molar in two of 

 the extinct species of Kangaroo (ib. figs. 29, 30), which I next proceed to define. 



§ 2. Macropus Titan, Ow. — This species was founded on a portion of the right ramus 

 of a lower jaw from the Breccia-cave in Wellington Valley, New South Wales; in 

 which jaw, notwithstanding the superiority of size of the molar and of the portion of 

 molar in place to any of those in Macropus major, I was led from certain indications of 

 immaturity to ask permission from the possessor and discoverer of the then (183G) unique 

 fossil to excavate the substance of the bone; this being granted, led to the detection of 

 the nearly complete premolar or successional tooth in its formative alveolus, such as is 

 figured in vol. ii. pi. 29. fig. 3 of Sir Thomas Mitchell's work*. 



The discovery of the premolar was a satisfactory addition to the less conspicuous dif- 

 ferences in the molars of the present as compared with those in the fossil jaw of a 

 similarly sized extinct Kangaroo, also in Sir Thomas Mitchell's collection, on account 

 of the remarkably large and complex character of the premolar in that fossil, now the 

 type of Sthenurus (Macropus) Atlas (comp. fig. 18,^) 3 with fig. 4, p 3, Plate LXXXIL). 

 But I had not at that time the further satisfaction of determining the characters of the 

 maxillary dentition of Macropus Titan by fossils of that species, either at the corre- 

 sponding immature stage of the animal affording the mandibular fragment or of full- 

 grown individuals. I have subsequently received both desiderata, some of which 

 reached me in time to notice in the under-cited workf, and of which figures are now 

 for the first time given. The maxillary specimen (Plate LXXXI. figs. 6-9), in its phase 

 of dentition, relates as closely to the mandibular one (Plate LXXXIL figs. 17, 18) as 

 does the upper jaw of Sthenurus Atlas (Plate LXXXIV. figs. 4 & 5) to the portion of 

 lower jaw (Plate LXXXIL figs. 3 & 4). 



The fossil in question (Plate LXXXI. figs. 6-9) is not from the Breccia-cave of Welling- 

 ton Valley, but from a freshwater bed at Gowrie, Queensland, where it was obtained and 



* Three Expeditions into the Interior of Eastern Australia, &c. 8vo. 1838, vol. ii. p. 360 (2nd edit. 

 1839, p. 366, pi. xlvii.). 



f Catalogue of the Fossil Mammalia and Birds in the Museum of the Royal College of Surgeons, 4to, 

 1845, p. 324, Nos. 1500 and 1510. 



