PROFESSOR OWEN ON THE SPECIES OF PHASCOLOMYS. 487 
But, in both specimens, as in the skeleton of the Tasmanian Wombat (tom. cit. p. 330; 
no. 1792), the two anterior vertebra only are sacral by the character of abutment 
against and syndesmotic junction with the iliac bones. 
In an old individual of Phascolomys vombatus I have seen, and figured', a sacrum of 
seven vertebre by anchylosis of the centrums. Of these the first four repeat the cha- 
racters of the four sacrals in Phascolomys latifrons by coalescence of the terminally 
expanded diapophyses; those of the three succeeding vertebre are retroverted and 
anchylosed together. Moreover the articulation with the ilia is extended along the 
expanded anchylosed end of the four anterior sacrals. 
But under all these modifications the homologies of the respective vertebre (as indi- 
cated by the symbols, s 1-c 3) in both bare-nosed (fig. 3) and hairy-nosed (fig. 1) Wombats 
are unmistakable; and we discern, in the degree in which the caudal characters are 
assumed by the vertebrae succeeding the four anchylosed sacrals in Phascolomys latifrons, 
that the general character of the sacro-caudal region of the spine in Marsupialia is least 
departed from in that species. 
The tail is short and inconspicuous in all kinds of Wombat. Reckoning the series of 
vertebre to begin after the fourth sacral, there are not more than eleven caudals; and 
the two or three terminal ones are mere tubercular rudiments of the centrum. 
Bones of the Fore Limbs.—The clavicle in Phascolomys (Plate LXIX. figs. 12, 13) is 
a long, strong, slightly bent and twisted bone, expanded at both ends, but chiefly at the 
sternal one (ib. a). This is deeply canaliculate, the groove (ib. 6) opening upon the fore 
or outer surface of the bone. The sternal end (a, 4) is larger, and the groove is less and 
shorter in Phascolomys latifrons (ib. fig. 12) than in Phascolomys platyrhinus (ib. fig. 13) ; 
and the convex articular part forms a larger proportion of that end. The shaft of the 
bone is triedral in Phascolomys latifrons; it is subcompressed in Phascolomys platy- 
rhinus, in which the bone is flatter on the fore or outer surface, and is more convex on 
the opposite surface. The longitudinal bend is somewhat greater in Phascolomys 
platyrhinus (fig. 13); the acromial end is also flatter and rather broader in this species 
(ib.), and the two surfaces for ligamentous attachment to the acromion are more distinct 
and further apart than in Phascolomys latifrons. 
The scapula of Phascolomys (Plate LX XI.) maintains the form of a pretty regular 
quadrilateral plate nearly as far forward as the attachment of the spine extends (ib. e, f, 
figs. 1 & 4), the length of the quadrilateral being one third greater than the breadth in 
Phascolomys platyrhinus (figs. 4, 5), and nearly one half greater in Phascolomys latifrons 
(figs. 1,2). The hind border (a, a’) is continued on straight, or nearly so, to the glenoid 
cavity; the fore border (4, d') gives the length of the quadrilateral plate by its parallelism 
with the hind one, and is then continued on by a deep and large emargination (c) to 
the base of the coracoid (h); this emargination defines what may be termed the ‘ neck 
of the scapula.’ . The upper border or ‘ base’ (d) is straight, and at right angles to a and 3. 
1 Anatomy of Vertebrates, vol. ii. p. 331, fig. 213. 
3yY2 
