424 FEOFESSOE OWEN ON MACEOPUS. 



uniting with the paroccij^ital process of the alisphenoid. The lacrymal has a small 

 "facial" (ib. fig. 1, 73') and a large "orbital" plate (73); the angle between the two 

 shows two foramina with an intervening tubercle ; and in some species of Kangaroo there 

 is a second tubercle above the upper foramen. These lacrymal foramina (ib. fig. 2, /, /') 

 are rather ectorbital than entorbital ; both lead to a canal descending and bending 

 forward to terminate in the nasal meatus. 



The angle of the lower jaw (ib. fig. 1, a) is tumid, strongly inflected and upbent into 

 a ridge bounding a wide and deep concavity, indicated by as strong a convexity (k) ex- 

 ternally. The fore part of the cavity communicates with the external crotaphyte fossa 

 (f) by a perforation, in front of which is the entry of the dental canal. The symphysis 

 is long, narrow, and usually rather loose, permitting movements of the rami on each 

 other ^ There are no subsymphysial foramina as in Phascolomys. 



The vertical extent of the ramus increases from behind the last molar (ot 3) to the 

 antepenultimate one (m 1) ; it suddenly decreases in front of the molar series, and is 

 continued forward along an extensive diasteme {I, I), chiefly devoted to the motion of 

 the socket of the long procumbent incisor (/'). The external orifice of the dental 

 canal (y) is a little in advance of the molar series. 



The skull which forms the subject of PI. LXXIV. is from a male of a Great Rufous 

 Walleroo, which was killed by the eminent ornithologist, Mr. John Gould, F.R.S., 

 in a locality explored by him between the rivers Murray and Adelaide, Australia. 

 The animal measured 8 feet 2 inches from the nose to the extremity of the tail, and 

 was the largest Kangaroo which Mr. Gould saw in Australia. 



This animal had the last molar in place and use, and still retained, though much 

 worn down and probably soon to be shed, the tooth answering to the last of the 

 deciduous series in Diphyodont Mammals (ib. fig. 6, d i); the phase of dentition 

 answers to that marked F in my article " Odontology," in the ' Encylopsedia Britannica ' 

 (vol. xvi. p. 484) — the teeth, according to the symbols there adopted and explained, 

 being d 4, m 1, m 2, m 3; consequently three of the molar series, viz. ^ 3, (Z 3, and d 2, 

 had been shed. 



The four retained molars on the left side of the upper jaw present the two chief 

 transverse ridges as in the lower jaw ; but they are broader in proportion to their length 

 than in that jaw, and the curve of the ridges (as shown in m 3, fig. 3) where they are 

 least worn is slightly concave backward, instead of forward as in the lower jaw 



' " The Mus maritimus, or African Eat, has the singular property of separating at pleasure to a considerable 

 distance the two front teeth of the lower jaw, which are not less than an inch and a quarter long. That 

 elegant and extraordinary creature, the Kangaroo, which, from the increase that has lately taken place in his 

 Majesty's Gardens at Kew, we may soon hope to see naturalized in our own country, is possessed of a simOar 

 faculty." — Mason Good, The Book of Nature, 8vo, 1826, vol. i. p. 285. This power of divaricating the lower 

 incisors, or rather their sockets, through laxity of the ligamentous symphysial joint, has siuce been noticed by 

 Waterhoxise (N"at. Hist, of the Mammalia, 8vo, 1845, vol. i. p. 52), and by myself and others. 



