282 - 
We find, therefore, that the bones of the fore- 
arm of the Kan differ little from those of 
the burrowing Wombat, the climbing Koala, or 
be eee hear we, save in ror =~. 
present the greatest proportional strengt 
in the Wombat, and the soiree proportional 
length and slenderness in the Petaurists or Fly- 
ing Opossums, in which the radius and ulna are 
in close contact through a great portion of their 
extent, and thus lend a firmer support to the out- 
stretched dermal parachute. They are also long 
and slender inthe Koala. In general the radius 
and ulna run nearly parallel, and the interos- 
seous space is very trifling. It is widest in the 
Potoroos. The olecranon is well developed in 
all the Marsupials. Inthe Virginian Opossum 
and Petaurists we find it more bent forwards 
upon the rest of the ulna, than in the other Mar- 
supials. Inthe Wombat, where the acromion is 
the strongest, and rises an inch and a half above 
the articular cavity of the ulna, it is extended 
in the axis of the bone. The distal end of the 
radius in this animal is articulated to a bone 
representing the os scaphoides and os lunare. 
The ulna, which in the same animal con- 
verges towards a point at its distal end, has that 
point received in a depression formed by the 
cuneiform and pisiform bones ; these are bound 
together by strong ligaments, and the pisiform 
then extends downwards and backwards for 
two-thirds of an inch. The second row of the 
carpus consists of five bones. The trapezium 
supports the inner digit, and has a small sesa- 
moid bone articulated to its radial surface. 
The trapezoides is articulated to the index digit, 
and is wedged between the scapho-lunar bone 
and os magnum; this forms an oblique articu- 
lar surface for the middle digit; but the largest 
of the second series of carpal bones is cuneiform, 
which sends downwards an obtuse rounded 
process, and receives the articular surface of 
the fifth, and the outer half of that of the 
fourth digit, the remainder of which abuts 
against the oblique proximal extremity of the 
middle metatarsal bone. 
The five metacarpal bones are all thick and 
short, but chiefly so the outermost. The inner- 
most digit, or pollex, has two phalanges, the 
remainder three ; the ungueal phalanx of all the 
digits is conical, curved, convex above, ex- 
panded at the base, and simple at the opposite 
extremity. 
In the-Perameles the ungueal phalanx of the 
three Thiddle digits of the hand, and of the 
two outer digits of the foot, are split at the 
extremity by a longitudinal fissure commencing 
at the upper part of the base. This structure, 
which characterizes the ungueal phalanges in 
the Placental Anteaters, has not been hitherto 
met with in other Marsupial genera.* 
The terminal phalanges of the Koala are 
large, much compressed and curved ; the con- 
cave articular surface is not situated, as in the 
cats, on the lower part of the proximal end, 
but, as in the sloths, at the upper. The claws 
which they support are long. 
* It would be interesting to examine the skeleton 
of the Cheropus, with reference to this structure. ~ 
MARSUPIALIA. 
In the Great Kangaroo the first row of the 
carpus is composed, as in the Wombat, of thr 
bones, but the apex of the ulna rotates in a 
vity formed exclusively by the cuneiforme 
There are four bones in the second row; of 
which the unciform is by far the largest, and 
supports a part of the middle, as well as th 
two outer digits. Inthe Potoroos I find t 
three bones in the distal series of the carpus 
the trapezoides being wanting, and its place in 
one species being occupied by the proximal en 
of the second metacarpal bone, which articulates 
with the os magnum. In the Perameles there 
are four bones in thesecond carpal row, although 
the hand is less perfect in this than in any other 
Marsupial genus, Cheropus excepted, the three — 
middle toes only being fully developed. 
In the Petaurists the carpus is chiefly re 
markable for the length of the os pisiforme. — 
It would be tedious to dwell on the minor 
differences observable in the bony structure of 
the hand in other Marsupials. I shall there- 
fore only observe that though the inner digit 
is not situated like a thumb, yet that the fingers 
enjoy much lateral motion, and that those at 
the outer can be opposed to those at the inner 
side so as to grasp an object and perform, ina 
secondary degree, the function of a hand. In 
the Koala the two inner digits are more deci- 
dedly opposed to the three outer ones than in — 
any other climbing Marsupial. But some of — 
the Phalangers, as the Ph. Cookit and Ph. 
gliriformis of Bell, present in a slighter de- 
gree the same disposition of the fingers, by — 
which two out of the five have the opposable — 
properties of a thumb. I have observed a 
similar disposition of the digits in the act of 
climbing in the Dormouse, and it probably is 
not uncommon in other placental Mammalia of — 
similar habits and which have long, slender, — 
and freely moveable fingers. As a permanent 
disposition of the digits, the opposition of 
three to two is most conspicuous in the pre- 
hensile extremities of the Chameleon. ‘ 
Of the Pelvic Extremities—The pelvis ( 
109) in the mature Marsupials is com f 
the os sacrum, the two ossa innominata, and the — 
characteristic supplemental bones, attached to — 
the pubis, called by Tyson the ossa marsupialia 
or Janitores Marsupii. ‘ 
We seek in vain for any relationship be- 
tween the size of the pelvis and that of the 
new-born young, the minuteness of which is 
so characteristic of the present tribe of animals. 
The diameters both of the area and apertures 
of the pelvic canal are always considerable, 
but more especially so in those Marsupialia — 
which have the hinder extremities dispro: 
tionately large ; as also in the Wombat, where — 
the pelvis is remarkable for its width. The 
elvis is relatively smallest in the Petaurists; 
at even here the diameter of the outlet is at 
Hiss 
foramina by an osseous bridge continued from — 
