144 



three, developed, of very small size, on the inner side of the fore part of the lower car- 

 nassial ; and 1 have seen no specimens of mandible in which they are retained. 



Photographs and Cave-specimens of the Mandible and Mandibular Teeth. — The 

 following are the most instructive photographs of portions of the mandible with 

 teeth of Thylacoleo from the Breccia-cave of Wellington Valley, in the series above 

 referred to. 



No. 10 gives two views of a portion of the right ramus (the outside view is given in 

 Plate IX. fig. 1 ). It is similar to the fossil from Queensland above described (Plate VIII. 

 fig. 1), but more mutilated at the back part. The chief value of the specimen photo- 

 graphed is the retained incisor (?), from which only the apex of the crown is wanting, 

 by an oblique fracture from above and behind downward and forward. In a photograph 

 of a more mutilated mandible (ib. fig. 2), the inner wall of the alveolus of the incisor 

 is broken away as far as the vertical line dropped from the fore part of the carnassial 

 (p <). The outer wall remains a few lines in advance of this in the subject of figure 1, 

 but sufficient of the cement-covered root of the tooth is exposed to show a commencing 

 contraction toward its implanted end. The incisor is directed upward at an angle of 

 130° with the long axis of the ramus, and the crown shows a curvature with the convexity 

 forward and downward as in the lower laniaries of Thylacinus ; the hind border is not 

 straight or convex like the answerable upper border in the same tooth of Bettongia 

 and Hypsiprymnus, but is serrato-trenchant and slightly concave lengthwise. A photo- 

 graphic view giving the transverse breadth or thickness of the incisor would have been 

 instructive ; but the portion of the tooth retained in the mandibular ramus figured in 

 Plate VIII. fig. 1, i, a, shows the more essential distinction from the long procumbent 

 lower incisors of the herbivorous Marsupials in the degree of lateral compression of 

 the crown and its proportion to the anteroposterior breadth, which in the laniary of 

 Thylacoleo is intermediate between that in Machairodus and Felis. 



The two anterior outlets of the dental canal are present, and in the same position in 

 the cave-fossil (Plate IX. fig. 1, 0) as in the Queensland specimen (Plate VIII. fig. 1, 0). 

 The postero-inferior emargination of the symphysial surface is repeated on the inner 

 surface of the ramus of the subject of fig. 1, Plate IX., as in Plate VIII. fig. 2, r. 



All the characters of the carnassial tooth (p *) in the Queensland specimen are closely 

 repeated ; the crown is abraded in the same direction and to the same extent. 



The crown of the first molar (m 1) is preserved in both the cave-specimens photo- 

 graphed, showing its raised, anterior, subtrenchant lobe, and its small low hind tuber- 

 cular talon. On the outer side of this tooth is shown the subvertical surface formed by 

 attrition against the hind part of the upper carnassial. The proportions of the anterior 

 and posterior roots of m 1 are indicated in the photograph of the inner side of the subject 

 of fig. 1, Plate IX. The socket of the minute^? 3 (ib.) plainly appears on the inner 

 side of that for the anterior root of p 4 in the same photograph ; but the shallower and 

 larger ones of p 2 and p 1 have left no impression — were probably obliterated in the 



