PROFESSOR OWEN OX THE SPECIES OF PHASCOLOMTS. 487 



But, in both specimens, as in the skeleton of the Tasmanian Wombat (toni. cit. p. 330i 

 no. 1792), the two anterior vertebra3 only are sacral by the character of abutment 

 against and syndesmotic junction with the iliac bones. 



In an old individual of Phascolomys voinbatus I have seen, and figured ', a sacrum of 

 seven vertebrae 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 vertebrae 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 vertebra; (as indi- 

 cated by the symbols, s i-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. Beckoning the series of 

 vertebrae 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. b) opening upon the fore 

 or outer surface of the bone. The sternal end [a, b) 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 sui-faces for ligamentous attachment to the acromion are more distinct 

 and further apart than in Phascolomys latifrons. 



The scapula of Phascolomys (Plate LXXI.) 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 [b, b') 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 b. 

 ' Anatomy of Vertebrates, vol. ii. p. 331, fig. 213. 



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