272 
meles and Potoroos the sphenoid ale do not 
reach the parietals. 
There is little to notice in the parietal bones 
except the obliteration of the sagittal suture in 
those species in which a bony crista is deve- 
loped in the corresponding place. They pre- 
Sent a singularly flattened form in the Wombat, 
in an aged skull of which, and in a similar one 
in the Kangaroo, I observe a like obliteration 
of the sagittal suture. In the Kangaroo, 
Potoroo, Petaurus, Phalanger, and Myrme- 
cobius there is a triangular inter-parietal bone. 
The corresponding bone I find in three pieces 
in the skull of a Wombat. 
The frontal bones are chiefly remarkable for 
their anterior expansion and the great share 
which they take in the formation of the nasal 
cavity. In the Thylacine the part of the cranium 
occupied by the frontal sinuses exceeds in 
breadth the cerebral cavity, from which it is 
divided by a constriction. The coronal suture 
presents in most of the Marsupials an irregular 
angular course, forming a notch in the frontals 
on each side which receives a corresponding 
triangular process of each, parietal bone: this 
form of the suture is least pronounced in the 
Acrobates and Myrmecobius. A process cor- 
responding to the posterior frontal augments 
the bony boundary of the orbit in the Thylacine, 
the Ursine Dasyure, and in a slighter degree 
in the Virginian Opossum ; it is relatively most 
developed in the skull of the Myrmecobius 
Jasciatus, where the orbit. is large; but the 
bony boundary of the orbit is not complete in 
any of the Marsupials. In the Myrmecobius 
there is a deep notch at the middle of the 
supra-orbital ridge. A corresponding but 
shallower notch is present in the skull of 
Petaurus sciureus. have found the frontal 
suture obliterated in old specimens of the 
Thylacine, the Virginian Opossum, Cook’s Pha- 
langer, the taguanoid, and yellow-bellied Pe- 
taurists; but the frontal suture exists in Petaurus 
Sciureus, Acrobates, and other Marsupials. 
The inter-orbital space is concave in the Pha- 
langers and in the Petaurus Taguanoides, but 
is quite flat in the other Petaurists. 
e lachrymal bones vary in their relative 
size in different Marsupialia. In the Koala 
they extend upon the face about a line beyond 
the anterior boundary of the orbit, and at this 
part they present a groove with one large and 
two or three small perforations. In the Wom- 
bat their extent upon the face is slightly in- 
creased; it is proportionally greater in the 
Kangaroos, Potoroos, Phalangers, Petaurists, 
and Dasyures, in which this part of the 
lachrymal bone presents two perforations close 
to the orbit. In the Thylacine, besides the 
two external holes there is a large perforation 
within the orbital margin. This carnivorous 
Marsupial, as compared with the Wolf, pre- 
sents a greater extent of the facial portion of 
the lachrymal bone, and thus indicates its 
inferior type. In the Myrmecobius the lachry- 
mal bone exhibits its greatest relative develop- 
ment. 
The malar bones are very strong and of great 
extent in almost all the Marsupialia. They 
MARSUPIALIA. 
are least developed in Acrobates, 1] 
cobius, and Perameles lagotis. In the latt 
the malar bone presents a singular form, b 
bifurcate at both extremities: the proces 
zygomaticus maxille superioris is wedged 
the cleft of the anterior fork; the correspor 
ing process of the temporal bone fills up 
sterior notch; the lower division of — 
ifurcation is the longest, and in all the ¥ 
supialia enters into the composition of 
articular surface for the a 
the Petaurists, where it just 
The anterior bifurcation of the & 
one is not present in the Marsupials ger 
the external malo-maxillary suture fe 
oblique and almost straight line in the Wom 
Phalanger, Opossum, Dasyures, and Kangar 
Owing to the inferior development of the zy; 
matic process of the superior maxillary in | 
Wombat, the malar bone is not suspen 
the zygomatic arch in this Marsupial as in 
placental Rodentia. It is also of ’ 
much larger size and of a prismatic 
arising from the development of the ¢ 
external ridge above described. In the 
garoos, Potoroos, Great Petaurus, and — 
langers it is traversed externally by a & 
showing the extent of attachment of 
masseter; in the Koala the ridge extends al 
the malar bone near the upper margin, — 
surface below presents a well-marked exes 
tion. 4 
The nasal bones vary in their form and 
tive size in the different genera ; they are lor 
and narrowest in the Perameles, short 
broadest in the Koala. Their most 
teristic structure is the expansion of their 
and posterior extremity, which is well mai 
in the Wombat, Myrmecobius, " 
Phalangers, Opossums and Dasyures. 
In the Potoroos the anterior extremitie: 
the nasal bones converge to a point which } 
jects beyond the inter-maxillaries. In s§ 
Petaurists and Perameles the correspon¢ 
ints reach as far as the inter-maxillaries, 
in a skull of the Perameles lagotis I have fe 
the bony case of the nasal passages to be fu 
increased by the presence of two small ros 
bones, resulting, as in the Hog, from os 
of the nasal cartilage. 
The inter-mazillary bones always ec 
teeth, and the ratio of the development of t 
bones corresponds with the bulk of the de 
apparatus which they a They are 
sequently largest in the Wombat, where 
extend far upon the side of the face and 
articulated to a considerable proportion of 
nasal bones, but do not, as in the plac 
Rodentia, reach the frontal or divide 
maxillary bone from the nasal. yD 
sent a somewhat lower degree of develop 
in the Koala, but both in this species 
in the Wombat they bulge outwards and - 
remarkably increase the transverse diam 
of the osseous cavity of the nose. Ne 
in Hypsiprymnus nor Macropus do I f 
the incisive palatal foramina entirely im 
intermaxillary bones, as is descri t 
author of the text in Pander and D’Alto1 
