488 



Palorchesles. Macropus rufus. 

 Breadth of median surface of ilium below symphysial in. lines. in. lines. 



surface , ' ... I* V ' t,l,%'-' t 20 10 



Length of acetabulum 28 17 



Breadth of acetabulum 20 14 



Breadth of ischium behind the lower part of acetabulum .22 13 



§3. Macropus 1 . (Scapula). — In a series of fragmentary fossils from drift-deposits of 

 Darling Downs the articular end of a left scapula with the glenoid cavity and the 

 acromial end of the spine shows a greater relative height of that part than in Macropus 

 rufus (Plate LXX. fig. 2). The breadth of the neck of the scapula in that large living 

 species is twice the height of the fore part of the spine; in the fossil it is only one 

 third more. The fore part of the spine in the fossil springs from the dorsal surface of 

 the bladebone relatively nearer to the concave border of the upper costa than in 

 Macropus rufus. In other respects the correspondence is close, save in size. In the 

 latter character the present fossil might well belong to a Macropus Titan. 



§4. SthenurusX (Scapula). — The corresponding part of a right scapula belongs to a 

 distinct species. The glenoid cavity is broader and deeper in proportion to its length. 

 There is an oblong depression at the cervical part of the lower costa, not present in the 

 preceding fossil, nor in the scapula of Macropus rufus. The degree of difference may 

 indicate this fossil to have belonged to a Sthenurus Atlas. 



§5. Phascolagus ? (Humerus). — This bone in existing Kangaroos (Plate LXIX., 

 Macropus rufus) has long been noted by the Comparative Osteologist as an exception 

 to the supposed rule that the perforation of the entepicondyle (ib. s, i) was a charac- 

 teristic of that bone in certain members of the placental Carnivora *. The perforation 

 relates, however, though not absolutely, as is now well known, to the degree of trans- 

 verse expansion of the distal end of the humerus needed for adequate surface of 

 attachment of muscles concerned in the application of the fore paw in rotatory move- 

 ments. But such movements may effect, and be required by, other purposes than the 

 catching, holding, and killing a prey. In the Kangaroos they relate mainly to the 

 manipulations of the pouch, but give a power to the fore limb in other vegetable- 

 feeding Marsupials in acts of burrowing (Phascolomys) and climbing (Phascolarctos). 



The generic characteristics of the humerus mMacropodidce are given at pp. 387, 388, 

 and are illustrated by figures of that bone in one of the largest of the existing species, 

 Macropus (Osphranter) rufus (Plate LXIX.). 



I commence the descriptions of the modifications of this bone in extinct Kangaroos 

 by the subject of Plate CXI. It was obtained from the bed of King's Creek, Darling 

 Downs, and was presented by Frederic Neville Isaac, Esq., to the British Museum. 



* Cttvieb, ' Ossemens Fossiles,' 4to, vol. iv. p. 284 (1825). In the posthumous 8vo edition the editor adds 

 to the carnivorous genera there cited, " ainsi que dans les Didelphes et tous les animaux a hourse " (vol. vii. 

 p. 270). But there are exceptions in the Marsupial order, as, e. g., in Dasyurus Maugei, Phalanyista Cookei, 

 Petaurus sciureus. See my 'Anatomy of Vertebrates,' vol. ii. p. 352 (1866). 



