147 



Thus the perforating part of this tooth is strengthened by four longitudinal enamel 

 ridges, in which the serrate or finely undulated or wrinkled character is more or less 

 manifest, especially on the trenchant anterior border, defining the outer (fig. 5) from the 

 inner (figs. 4 & 6, i) surfaces of the crown, also on the supplementary ridge (d) on the 

 inner facet (i). 



As the fore-and-aft breadth of the crown increases from the apex downward, the 

 stronger convexity of the antero-external part is limited to the fore part of that facet, 

 the hinder part of the facet becoming less convex or almost flattened, and at the base 

 of the crown even feebly concave, where the cement (fig. 5, c) encroaches on the enamel. 

 A similar concavity marks the outer part of the base of the laniariform incisor of Phi- 

 giaulax, Falconer, X. fig. 1, p. 366 ; XI. pi. 33. fig. 1, a. The anterior subserrate 

 ridge is the longest, the postexternal ridge subsides a little sooner in approaching the 

 base, the postinternal ridge is next in length, and the supplementary inner ridge is the 

 shortest. The enamel-case of the crown is entire, but is thickest upon the more convex 

 anterior part of the antero-external facet, and where it forms the ridges (see the section, 

 Plate IX. fig. 8). 



The posterior facet at the apical part of the crown meets at a right angle the inner 

 side, but lower down it slopes from the postinternal ridge, backward as well as outward, 

 to meet the outer facet at b. This gives a more trenchant character to the subserrate 

 ridge or border (d) between these surfaces. 



The effective cutting power of the postinternal ridge, where the angle between the 

 posterior and internal surfaces of this three-sided bayonet-like tooth becomes a little 

 open, is enhanced by the prominence of the ridge, supplemental strength being given 

 to the piercer by the added postinternal ridge. The cement-clad root (Plate IX. 

 figs. 5, 6 & 7, c,f) gradually contracts to its subtruncate closed extremity. 



In the specimens of lower laniary above described, as in the cast and photographs of 

 that formidable tooth of Thylacoleo, evidence is given of its conforming in its limited or 

 temporary growth, as in its shape, proportions, and structure, with the canine of the 

 Felines, but with superadded modifications strengthening and perfecting it for its work 

 as a piercer, holder, and lacerator. 



Thus, through the cooperation of a liberal and enlightened Legislature and Adminis- 

 tration, and of esteemed friends and fellow-labourers, in Sydney, New South Wales, ample 

 evidence has been got of both upper and lower laniary incisors, as well as of the rest of 

 the dentition of Thylacoleo carnifex. 



It is with pleasure, though without surprise, that I have been enabled to confirm the 

 inferences expressed in my former papers, on such elements of that dentition as I then 

 only knew " in part." 



Whether the " principles which are followed as guides in this walk of investigation 

 were" therein " set aside, to give place to the illusory indications of mutilated external 

 form"*, I cannot determine, because Dr. Falconer does not define the principles to which 



* X. p. 354; XI. p. 437. 



