OF THE MARSUPIALIA. 387 
greater in the Kangaroos, Potoroos, Phalangers, and Dasyures, in which this part of the 
lachrymal bone presents two perforations, but it is close to the orbit. The Thylacine, 
as compared with the Wolf, presents a greater extent of the facial portion of the lachry- 
mal bone, and thus indicates its inferior type. In the Myrmecobius the lachrymal bone 
exhibits its greatest relative development. 
The malar bone is very strong, and of great extent, in all the Marsupiata. Least 
developed in the Perameles lagotis, it here presents a singular form, being bifurcate at 
both extremities: the processus zygomaticus mazille superioris is wedged into the cleft of 
the anterior fork ; the corresponding process of the temporal bone fills up the posterior 
space: the lower division of this bifurcation is the longest, and in all the Marsupiata 
enters into the composition of the articular surface for the lower jaw, except in the 
Petaurists, where it just falls short of this part. The anterior bifurcation of the malar 
bone is not present in the Marsupiata generally: the external malo-maxillary suture 
forms an oblique and almost straight line in the Wombat, Phalanger, Opossum, Dasy- 
ures, and Kangaroo. Owing to the inferior development of the zygomatic process of the 
superior maxillary in the Wombat, the malar bone is not suspended in the zygomatic 
arch in this Marsupial, as in the placental Rodentia. It is of relatively much larger 
size, and of a prismatic form, arising from the development of the oblique external 
ridge above described. In the Kangaroo, Potoroo, Great Petawrus, and Phalanger, it is 
traversed externally by a ridge, showing the extent of attachment of the masseter: in 
the Koala it extends along the bone, near the upper margin, and the surface below 
presents a well-marked excavation. 
The nasal bones vary in their form and relative size in the different genera ; they are 
longest and narrowest in the Perameles; shortest and broadest in the Koala. Their 
most characteristic structure is the expansion of the upper and posterior extremity, 
which is well marked in the Wombat, Myrmecobius, Petaurists, Phalangers, Opossums, 
and Dasyures. 
In the Potoroos the anterior extremities of the nasal bones converge to a point, which 
projects beyond the intermaxillaries. In some Petaurists and the Perameles the corre- 
sponding points reach as far as the intermaxillaries, and in the skeleton of an old Pere- 
meles lagotis I found that the bony case of the nasal passages is further increased by the 
presence of two small rostral bones, resulting, as in the Hog, from ossification of the 
nasal cartilage. 
The intermaxillary bones always contain teeth, and the ratio of their development 
corresponds with the bulk of the dental apparatus which they support. They are con- 
sequently largest in the Wombat, where they extend far upon the side of the face, and 
are articulated to a considerable proportion of the nasal bones, but do not, as in the 
placental Rodentia, reach the frontal, or divide the maxillary bone from the nasal. 
They present the next degree of inferior development in the Koala, and both in this 
species and in the Wombat bulge outwards, and thus remarkably increase the transverse 
