ei 
Il. Description of a Portion of Mandible and Teeth of a large extinct Kangaroo (Palor- 
chestes crassus, Ow.) from ancient fluviatile Drift, Queensland. By Prof. Owen, 
C.B., F.RS., F.ZS., &c. 
Received April 25th, read May 20th, 1879. 
[Puate II.] 
THE largest of the extinct kinds of Kangaroo (Macropodide)' 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 (Procoptcdon 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, while 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, m1, equals m2 in antero-posterior 
extent of crown; in Palorchestes crassus (Pl. Il.) m2 exceeds in that diameter m1 by 
one fifth; m2 is also relatively broader than m1 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 m2 is longer and broader in P. crassus ; and the same diffe- 
rential character marks m1, in comparison with that tooth in P. azael. This part of 
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 (4). 
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. 
1 Researches on the Fossil Remains of the Extinct Mammals of Australia, 4to, vol. i. p. 373. 
2 Op. cit. vol. i. p. 460, vol. ii. pls. xciv. & xcv. 
> Op. cit. vol. i. p. 466, vol. ii. pls. xevi. & xevii., cv.—cvii. 
