170 MWARSUPIALIA 
Wallabies, which are small and lightly-built animals, in some 
instances not larger than a Rabbit. Their muffles are always naked, 
and in the skull the anterior palatine foramina are small and the 
posterior vacuities very large, while the posterior expansion of the 
nasals is very marked. The third upper incisor is smaller than in 
the last group. This group extends farther into the tropics than 
either of the others, being found in the New Britain and Aru 
islands, as well as in New Guinea. J. brachywrus is remarkable for 
its comparatively short and slender tail and small ears. The earliest 
known species of Kangaroo, referred to before, I. brunt, belongs to 
this section. Several examples were seen by Bruyn in 1711 living 
in captivity in the garden of the Dutch governor of Batavia, and 
described and figured in the account of his travels (Reizen over 
Moskovie, ete.) under the name of “Filander.” It was quite lost 
sight of, and its name even transferred by S. Miiller to another 
species (Dorcopsis muelleri), until rediscovered in 1865 by Rosenberg, 
who sent a series of specimens to the Leyden Museum from the 
islands of Aru and Great Key, thus determining its true habitat. 
M. thetidis is a well-known Australian representative of this 
group. 
Extinct genera.—In addition to the fossil forms already mentioned 
which can be referred to existing genera, there are others from the 
Australian Pleistocene indicating extinct generic types of Macropod- 
ide, to which brief reference may now be made. The first of these 
is Sthenurus,) represented by a single large species (S. aélas), and 
characterised by the presence of a complete inner lobe to the fourth 
upper premolar, and of an outer one in the opposing lower tooth, 
so that these teeth present a flat and oval grinding surface when 
worn. The median longitudinal bridge connecting the transverse 
ridges of the molars is very imperfect; and in the upper molars 
there is no bridge between the first ridge and talon. In Procoptodon? 
the premolars resemble those of Sthenurus, but the molars are 
elongated, and usually have their enamel thrown into numerous 
vertical foldings. The most distinctive feature is, however, the 
complete ankylosis of the mandibular symphysis; the mandibular 
rami being deep, and the diastema in the dental series short. The 
lower incisors are nearly cylindrical, and the palate has large 
vacuities. Three species are known. The largest representation of 
the whole family is the type of the genus Pulorchestes® (P. azael), in 
which the length of the skull is estimated at sixteen inches. It is 
distinguished from Procoptodon by the longer mandibular symphysis 
and diastema, and the spatulate lower incisors. The true molars 
have no distinct anterior talon, and are not grooved, while the 
palate was fully ossified. 
1 Owen, Phil. Trans, 1874, p. 264. 
2 Owen, op. cit. p. 788. 5 Owen, op. cit. p. 797. 
