374 



In the present 'Section' I have selected those of the great Rufous Wallaroo {Macro- 

 pus rufiis, Desm. 1 , M. laniger, Gaimard 2 and Gould 3 ). 



§ 2. The Skull. — The skull in Kangaroos (Macropodidae, 0\v. *) is characterized by 

 the great length of the diastema between the molars and incisors in both jaws. A 

 minute rudiment of a canine, or a minute depression where such rudiments may have 

 been lodged, is present in some small kinds of Kangaroo, but is inconstant in them. 

 The skull (Plate LXVI.) is long, through the extension of the facial or maxillary part 

 in front of the orbits (fig. 1, o) ; and these cavities, interposed between the facial and 

 cerebral part, are large ; they widely communicate, as in the rest of the order, with the 

 temporal fossae (ib. t). The paroccipital (ib. figs. 1 & 4, 4) and masseteric (ib. 21 x) 

 processes are produced downwards — the former to an extreme degree, to which Phas- 

 eolarctos, perhaps, affords the nearest approach in the marsupial order. A sagittal 

 crest may be indicated in old males of some of the larger Kangaroos, but is never 

 elevated. The zygomatic arch is deep, with the malar (26) element, suspended between 

 the maxillary (21) and squamosal (27) piers. The malar contributes a small but definite 

 share (ib. fig. 3, 26*) to the outer part of the joint for the mandible, the entire articular 

 surface (27 a ) being subquadrate, feebly convex transversely, partially concave length- 

 wise, through the descent of a postglenoid process (ib. figs. 1, 3, jpg), internal to which 

 is a perforation. 



The alisphenoid (ib. fig.. 3, tr) sends down a process (ib. fig. 1, 6') abutting against 

 the paroccipital (4). The three compartments of the cranial cavity — epencephalic, 

 prosencephala, and rhinencephalic — succeed each other lengthwise ; and the olfactory 

 cavity extends backward both above and beneath the rhinencephalic fossa. The " sella 

 turcica " is indicated by the entocarotid foramina, not by clinoid processes. The basi- 

 occipital (ib. fig. 3, 1 ) is hexagonal, the hind border emarginate, forming the lower 

 fourth of that of the foramen magnum (ib. fig. 4, 0) and contributing a very small part 

 to each condyle (g). The exoccipital (ib. fig. 4, 2) develops the rest of that joint- 

 surface (g), which is oblong-convex, with an upper or back portion bent at a right angle 

 to the rest of the convexity. In young Macropodidae the superoccipital (ib. fig. 4, 3) 

 contributes a small share to the upper border of the foramen, which extends thereto by 

 a fissure-like prolongation upward, between the then separate occipitals. These, 



1 ' Mammalogie,' Supplement, p. 541 (1822). 



1 Bulletin des Sciences par la Societe Philomathique (18215), p. 138. 

 * ■ Mammals of Australia,' fol. part v. 



' Not the Macropida? of J. E. Gray, nor the Macropodidae of Waterhouse. The former term, like the Didel- 

 pliidse of De Blainville, is equivalent to the ordinal term " Marsupialia/' see ' Catalogue of the Bones of Mam- 

 malia in the collection of the British Museum,' 8vo, 1862, pp. 119-140. The latter term includes the Potoroos 

 (Hypsiprymnidaj) with the Kangaroos. The species, however, which have the dental formula i. c. ° 

 p. »".fE}> manifest, in the series of extinct with recent forms, so many generic modifications, that a name 

 for the canineless family of Poephaga is requisite. 



