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II. Description of a Portion of Mandible and Teeth of a large extinct Kangaroo (Palor- 

 chestes crassus, Oio.) from ancient fluviatile Drift, Queensland. By Prof. Owen, 

 C.B., F.E.S., F.Z.S., '&c. 



Kcci'ived April 2.5tli, read May HOtli, 1S79. 



[Plate II.] 



The largest of the extinct kinds of Kangaroo [Macropodidce) ' indicated by Australian 

 fossils showed a closer adherence to the typical pattern of the molar teeth than did 

 some of the extinct kinds of intermediate bulk {Procoptodon e. g.) '-. The genus and 

 species Palorchestes azael ^ were founded on two specimens — a large portion of the 

 cranium and a small portion of a mandible. 



Through the continued application of his leisure to the collection of fossils in his 

 Queensland locality, our Corresponding Member, George Frederick Bennett, Esq., of 

 Toowomba, has lately supplied me, amongst other instructive illustrations of the 

 extinct mammalian fauna of Australia, with a specimen which, whUe it is confirmatory 

 of the generic grade of Palorchestes, indicates a second species not inferior, at least 

 in size, to P. azael, but of more robust proportions. 



In Palorchestes azael the antepenultimate molar, m 1, equals wi2 in antero-posterior 

 extent of crown ; in Palorchestes crassus (PI. II.) m 2 exceeds in that diameter m 1 by 

 one fifth ; m 2 is also relatively broader than m 1 or m 3 (fig. 4). 



The cingulum (ib. fig. 1, c), continued from the outer side of the base of the fore lobe 

 to that of the hind lobe, of m 2 is longer and broader in P. crassus ; and the same diffe- 

 rential character marks ml, in comparison with that tooth in P. azael. This part ot 

 the cingulum is continued uninterruptedly from the fore part of the grinding-surface 

 of the tooth downward, outward, and backward, across the outer valley to the hind 

 talon of the crown (g). 



The antero-posterior extent of the three hind molars in P. crassus is 3 inches 7 lines 

 (92 millims.) ; in P. azael it is 3 inches 4 lines (85 millims.). 



If the dental differences had been only those of size, the fossil under consideration 

 might have been attributed to a larger individual than the type one, or to a male of 

 the species; but the difference in relative as well as absolute size of the comparable 

 teeth, as well as in the conformation of the tooth-crown, indicates something more than 

 difference of size or sex. 



' Researches on the Fossil Remains of the Extinct Mammals of Australia, 4to, vol. i. p. 373. 



' Op. cit. vol. i. p. 460, vol. ii. pis. xciv. & xcv. 



' Op. cit. vol. i. p. 466, vol. ii. pis. xcvi. & xovii., cv.-cvii. 



