357 



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. 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 (ns, 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 

 backward as a thick ridge (ib. fig. 5, pi). 



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

 the length and strength of the neural spine (PL XCVIII. 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 section, the 

 number of rib-bearing vertebrae 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 vertebrae in the bare-nosed Wombats 1 is exceptional in the 

 order. 



The first rib (PI. XCVIII. 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 (b), or, in other words, the 

 neck (c) is longest, in the first rib. The head shows, as in the succeeding ribs, two 

 articular facets («'), 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, b') larger and 

 more convex than in any of the other ribs ; and this fits the deep cup on the diapo- 

 physis of the first dorsal vertebra (ib. fig. 6, dl). There is a rough low tuberosity (ib. 

 fig. 7, d) on the middle of the outer or anterior surface of the first rib for the attach- 

 ment of a strong scalenus muscle. In the second rib (ib. fig. 8) besides the head (a), 

 neck (c), and tubercle (b), there is, on the outer border, at the same distance from the 

 tubercle as this is from the head, a second tubercle or process (e), smaller than the 

 normal one (b), and serving exclusively for muscular attachment ; it answers to what is 

 called the ' angle of the rib ' in anthropotomy. The articular surface on the tubercle 



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



34* 



