mammalia* 
51 
inner wftll. In other words, the hippocampus major, instead of being con- 
fined as it is, at least in the higher forms of placental mammals, to the middle 
or descending cornu of the lateral ventricle, extends up into the body of the 
ventricle, constituting its inner wall. 
2. The altered relation (consequent upon this disposition of the inner wall) 
and the very small development of the upper transverse commissural fibres 
(corpus callosuni). 
3. The great increase in amount, and probably in function, of the inferior 
set of transverse commissural fibres (^anterior commissure). 
■\ The paper is accompanied by three plates, showing vertical, 
transverse, and longitudinal sections of the brains of the animals 
mentioned. It elicited from Prof. Owen the remark that the 
presence of a corpus callosum in Marsupials has been denied by 
him from a zoological point of view only, and that its rudimen- 
tary condition not only has been observed but described by him 
in several anatomical treatises, Proc. Roy. Soc. 1865, p. 129. 
Mr. Flower replied to this, ibid. p. 134. 
APhascolomys. Dr. Murie (Proc. Zool. Soc. 1865, pp. 838-854) 
has examined the typical specimen of P. lasiorhinus (Gould), 
which had been living for some time in the Zoological Gardens 
in RegenPs Park. He took this opportunity of comparing it 
with other specimens (stuflPed examples and osteological prepara- 
tions) in the London collections, some of whicli had been used 
as types for sj)ccific descriptions ; and after having given an ac- 
count of the history of the species, he comes to the conclusion that 
only three species may be regarded as well established, the P. 
lasiorhinus being identical with P. latifrons (Owen) and the type 
of a distinct subgenus. The author gives the following generic 
and specific characters : — 
a. Fliascolomys (Geoffr.). Fur rough and coarse; muffle naked. Skull of 
moderate breadth in proportion to length ; postorbital ridge and frontal pro- 
cess obsolete ; nasal bones of moderate breadth ; supratympanic cavity mo- 
derately excavated ; foramen magnum of a trefoil figure. Upper incisor teeth 
forming one-third of a circle, and set with the enamelled surface chiefly out- 
wards. Dorsal vertebrte 16, lumbar vertebrae 4, and ribs 16 in number 1 
transverse processes of caudal vertebraj long and broad. 
1. Phascolomys womhat [Shaw]. Body of moderate size; sel- 
dom more than 3 feet long. Ears short and rounded. Colour dark 
grizzly greyish brown, produced by d.qrk-brownish hairs for the most part 
tipped with silvery grey, the longer ones with black points. Skull between 
6| and G| inches in length ; nasal bones relatively long and narrow ; supra- 
tj^mpanic excavation ver}’^ shallow ; postpalatine foramina oblong and of mo- 
derate size ; scapula long as compared with its breadth. 
2. Phascolomys platyrliinus (Owen) = P. mitclielli (Owen), fossil =P. 
latifrons (Gould) = P. setosus (Gray), pale var. = P. angasii (Gray), brown 
var. =P. niger (Gould), black var. Body large, generally above 3 feet long. 
Colour varying from pale yellowish brown (isabelline hue) to blackish brown, 
E 2 
