484 PROFESSOR OWEN ON THE SPECIES OF PHASCOLOMYS. 
perforates obliquely the neurapophysis (at ¢ 1, figs. 1 & 3), the aperture within the 
neural canal being above the articular concavity (¢’, 2’) for the occipital condyle. 
The transverse diameter of the atlas is less in proportion to its vertical one in Phasco- 
lomys latifrons (ib. figs. 1 & 2) than in Phascolomys platyrhinus (ib. figs. 3 & 4); the 
cups for the condyles (fig. 1, z/, z’) are less turned outward, and the diapophyses (ib. d, d) 
are more tuberous in Phascolomys latifrons; in Phascolomys platyrhinus (figs. 3 & 4, d, d) 
they are flattened below as well as above. The articular surfaces for the odontoid are 
more oblong and more nearly trausverse in Phascolomys latifrons (fig. 2, z',2'), and their 
outer border is not so much inclined backward as in Phascolomys platyrhinus (ib. fig. 4, 
z,z'). The unossified lower tract of the atlantal ring is greater in the bare-nosed 
Wombats (ib. figs. 3 & 4, h); but this character varies with age. Nevertheless in the 
atlas of the large old Phascolomys platyrhinus the interval is greater than in the atlas 
of the Phascolomys latifrons (ib. figs. 1 & 2, h), the skeleton of which shows fewer 
marks of age. 
The neurapophyses of the dentata are thicker and narrower from before backward in 
Phascolomys latifrons (ib. fig. 5, n) than in Phascolomys platyrhinus. In both species 
the neural spine (ib. 7s) is strongly developed in both height and anteroposterior 
breadth. That part in the succeeding cervicals is short and slender ; it is longer in the 
fourth (ns, 4) and seventh (fig. 6, ns, ¢ 7) cervicals in Phascolomys latifrons than in Phas- 
colomys platyrhinus. The pleurapophysis of the sixth cervical extends downward and 
backward as a thick ridge (ib. fig. 5, p /). 
In all existing Wombats the dorsal series begins with a sudden and great increase in 
the length and strength of the neural spine (Pl. LXIX. fig. 6,1). ‘The diapophyses 
(ib. d')are thickest in this vertebra and are deeply cupped at the end for the tubercle of 
the first rib. 
In the skeleton of the Phascolomys latifrons, described in the present ‘ Part,’ the 
number of rib-bearing vertebre is thirteen, leaving six for the lumbar series. In this 
particular the hairy-nosed species agrees with the majority of the Marsupialia. The 
greater number of dorsal vertebre in the bare-nosed Wombats’ is exceptional in the 
order. 
The first rib (Pl. LXIX. fig. 7) is the shortest and broadest; the last (ib. fig. 10) is 
the most slender and is least curved. The articular surface is retained on the tubercle 
(ib. figs. 7, 8, 9, 6) in the ten anterior pairs of ribs; only a trace of tubercle, rough for 
ligamentous attachment, is seen on the last three pairs. 
The costal head (ib. fig. 7, a) is furthest from the tubercle (6), or, in other words, the 
neck (c) is longest, in the first rib. ‘The head shows, as in the succeeding ribs, two 
articular facets (a'), which meet at a rather acute angle. Each side of the hind surface 
of the seventh cervical accordingly shows the facet (ib. fig. 6, p/) fitted to the anterior 
of those surfaces. ‘The tubercle presents an articular surface (ib. fig. 7, 0, 0’) larger and 
1 Phascolomys vombatus, e. g., Part I. tom. cit. p. 393. 
