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back ; it ends there below the interspace between the second (d 4) and third (m 1) molars. 

 The hind contour of the symphysis is subbilobed (ib. s,s*) ; it is long, but less deep relatively 

 than in Phascolomys Mitchelli (Plate LV. fig. 6). 



The grinding-surface of the anterior molar (Plate LII1. fig. 6, d 3) is subelliptic, with 

 the long axis nearly parallel with that of the jaw, 2 lines and 1 line in the two diameters, 

 showing the usual disposition of the incomplete coat of enamel. The succeeding molars 

 have the normal bilobed or biprismatic shape; their grinding-surfaces do not exceed 

 severally 3^ lines, the fore lobe of the first (d 4) and the hind lobe of the last (m 3) being 

 the Smallest. The hinder half of the diastemal tract, above, is bounded by a ridge (/) on 

 each side, and is there transversely concave. The outlet of the dental canal (Plate LIV. 

 fig. 6, v) is more advanced in position than in Phascolomys vombatus (Plate LII. 

 fig. 1, v). The outer enamelled surface of the incisor is transversely or vertically convex, 

 curving uninterruptedly to the lower border of the tooth, as in the bare-nosed Wombats, 

 but with less relative breadth of the tooth than in those existing species. Sufficient of 

 the angle of the jaw is preserved to show the partial division of the large cavity formed 

 by its inward extension into the inner (d) and outer (e) angular depressions (Plate 

 LVI. fig. 7). The base of the coronoid process (Plate LIV. figs. 6 & 7, c) is 6 lines in 

 fore-and-aft extent; in Phascolomys vombatus it is 11 lines. 



The well-marked characters of this small extinct species are satisfactorily repeated in 

 a second mandibular specimen, also of the left ramus, but more mutilated behind. It 

 retains, however, the anterior end entire ; and the incisor shows its worn surface (Plate 

 LIII. figs. 6 & 7, i). The vertical diameter of the incisor equals the long diameter of 

 the working-surface of the second molar tooth, d 4. 



A third illustration of this diminutive species is likewise afforded by a portion of the 

 left mandibular ramus ; it is a small portion, but includes the last two molars and the 

 hind half of the antepenultimate molar. The base of the common plate of the coro- 

 noid and condyloid processes is in part preserved, with a broken beginning of the ecto- 

 crotaphyte ridge : these, with the postalveolar ridge and ectalveolar groove, repeat the 

 characters of the more complete ramus (Plate LIV. figs. 6 & 7). The size of both bone 

 and teeth is the same in all. The present fossil, by the well-worn crowns of the molars, 

 appears to be from an old individual. The formal characters are incompatible with a 

 reference of those of size to immaturity. 



All the specimens of Phascolomys parvus were in the Boydian Collection of fossils 

 from the Lacustrine deposits of King's Creek, Darling Downs, Queensland, purchased by 

 the British Museum, and are in the same mineralized condition as the remains of Digro- 

 todon in the same collection. 



