484 FROFESSOE OWEN ON THE SPECIES OF PHASCOLOMTS. 



perforates obliquely the neurapophysis (at c i, figs. 1 & 3), the aperture within the 

 neural canal being above the articular concavity (r', 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 flatyrliinus (ib. figs. 3 &4); the 

 cups for the condyles (fig. 1, 2', z') are less turned outward, and the diapophyses (ib. fZ, 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 tramsverse in Phascolomys latifrons (fig. 2, z", z'}, and their 

 outer border is not so much inclined backward as in Phascolomys platyrliinus (ib. fig. 4, 

 z', z'). The unossified lower tract of the atlantal ring is greater in the bare-nosed 

 Wombats (ib. figs. 3 & 4, /*) ; 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. n s) 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 (hs, 4) and seventh (fig. 6, ns, c 7) cervicals in Phascolomys latifrons than in Phas- 

 colomys platyrhinus. The pleurapophysis of the sixth cervical extends downward and 

 backwai'd as a thick ridge (ib. fig. 5,^j I). 



In all existing Wombats the dorsal series begins with a sudden and great increase in 

 the length and strength of the neural spine (PI. 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 vertebrse 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 vertebrse in the bare-nosed Wombats' is exceptional in the 

 order. 



The first rib (PI. 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, b) 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 (5), 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, pi) fitted to the anterior 

 of those surfaces. The tubercle presents an articular surface (ib. fig. 7, b, V) larger and 

 ' Phascolomys vombatus, e. g., Part I. torn. cit. p. 393. 



