348 



The neck of the condyle at its origin (b) is but 9 lines across ; it expands to a breadth 

 of more than an inch where the condyle has been broken off. The base of the coronoid 

 process (c) has an antero-posterior extent of 1 inch 3 lines ; the anterior margin con- 

 tinued into that of the rising ramus subsides upon the outer surface of the jaw (q) below 

 the socket of the penultimate molar (m 2). 



The lower contour of the mandible (Plate LXI. figs. 1 & 2) describes a strong convex 

 uninterrupted curve to the fractured diastemal part, herein resembling rather the latifront, 

 or hairy-nosed, than the bare-nosed Wombats. 



The inflected angle (Plate LXIII. fig. 1, a) begins, posteriorly, at a lower level than 

 the ectocrotaphyte plate (ib. //), as in existing Wombats, but it has a minor relative extent ; 

 that of its base, as defined anteriorly by the " mylo-hyoid groove" (Plate LXI. fig. 2, w), 

 docs not exceed 2 inches ; consequently the superangular cavity (e) is relatively small. 

 The dental canal (Plate LX1I. fig. 4, 0) begins as a wide transverse fissure, internal to 

 which is the large vacuity above mentioned leading to the ectocrotaphyte fossa. The 

 postalveolar ridge (ib. t) forms a low angle as it bends to the superangular fossa. The 

 ectalveolar groove (ib. u) is relatively narrow. 



The depth of the horizontal ramus augments more rapidly to the back part of the 

 symphysis (Plate LXI. fig. 2, 6') than in recent or smaller extinct Wombats ; from 

 being 2 inches behind the last alveolus it grows to 3 inches 3 lines below the interval 

 between the penultimate and antepenultimate alveoli. The smooth thick lower border 

 shows prominences indicative of the matrices of the hinder molars, the bone being here 

 reduced to extreme thinness. The symphysis begins behind at a vertical line dropped 

 from the interspace between m 1 and m 2 ; it has been partially obliterated, the separation 

 of the rami here being attended with fracture of the confluent portion. This indicates an 

 aged animal. The hinder and upper border of the symphysis is divided into two curves 

 by the encroachment of the smooth inner surface of the ramus a little below the swelling 

 (i*) indicative of the closed and formative end of the socket of the incisor. The inter- 

 locking rough narrow ridges of the joint show the usual tendency to radiate from above 

 downward. There are two anterior outlets of the dental canal (in the subject of Plate 

 LXI. fig. 1, v) on the same vertical line, about half an inch in advance of the alveolus 

 of d 3 and near the diastemal margin. 



The length of the "ascending ramus" before dividing into the condylar and coronoid 

 processes shows a resemblance in the gigantic Wombat to the large herbivorous Noto- 

 there and Diprotodon, which is not seen in the smaller species of Phascolomys. The 

 bold curve of the lower contour of the " horizontal ramus " in Phascolomys gigas recalls 

 that feature of the mandible of the Megathere, and it has a like relation to the 

 lodgement of the formative matrices of long, ever-growing molars f . 



+ Should any successor deem the differential characters of the giant Wombat of generic or subgeneric value, 

 as the minor differences of Phascolomys latifrons have been by Dr. Murie (Proc. Zool. Soc. 18G7, p. 815), they 

 may, perhaps, accept the name ' PhascolonusJ having reference to the size of this species, which equalled that 

 of the Wild Ass. 



