134 



To my statement, " that there is a socket close to the symphysis of the lower jaw of 

 ThylacoleOy which indicates that the canine may have terminated the dental series there, 

 and afforded an additional feature of resemblance to the Plagiaulax"*, Dr. Falconer 

 remarks : — " In all this, it will be seen, the argument is within the domain of conjecture ; 

 the tooth oscillates between canine and incisor ; and not merely so, but the principles 

 which are followed as guides in this walk of investigation are set aside, to give place to 



the illusory indications of mutilated external form If pala)ontological investigations 



were conducted in this manner there would be no limit to conjecture ; the landmarks 

 we profess to follow would be disregarded, and disorder would face us everywhere. But, 

 happily, science furnishes unerring principles, which provide the corrective. I need 

 hardly add that the argument drawn from Thylacoleo has, in my view, no bearing on the 

 incisors of Plagiaulax, and gives no support to the carnivorous inference"f . 



This rebuke, being doubtless kindly meant and penned in the interests of palaeontology, 

 1 have hitherto borne in silence, hoping that less fragmentary fossils of Thylacoleo would 

 ultimately reach me ; and sustained, I must own, by a confident belief that they would 

 confirm the inferences drawn from the position of the alveolus, suggesting the alleged 

 feature of resemblance of Thylacoleo to Plagiaulax. 



Nevertheless, the portion of mandible figured in Plates xi. & xnr. of the Phil. Trans. 

 For 1859 being represented by a plaster cast, and the figures 5 & 6 in Plate iv. of the 

 Phil. Trans, for 1866 being from photographs, I could not feel surprised that arguments 

 in favour of the herbivorous nature and affinities of both Thylacoleo and Plagiaulax 

 should have met with acceptance and support from some Anatomists, Naturalists, and 

 Palaeontologists, as, for example, those referred to below J. 



I have again been favoured, through the kind offices of Sir Daniel Cooper, Bart., 

 with a collection of fossils obtained by his friend, Mr. St. Jean, of Gowrie, from the 

 freshwater deposits of that locality, in Darling Downs, Queensland, Australia, which 

 collection included the alveolar portion and certain teeth of the right upper jaw 

 (Plate VII. figs. 1-5), and the major part of the left ramus of the lower jaw with certain 

 teeth (Plate VIII. figs. 1-5) of a full-grown Thylacoleo carnifex. 



The teeth in the upper jaw are : — the anterior incisor with the terminal half of the 

 crown broken away (i i), the carnassial (p «), and three antecedent small and simple 

 obtusely conical teeth (p i, 2, 3). 



and Notes,' by the late Hugh Falconer, F.Il.S. &c., 8vo, 18G8, vol. ii. p. 437. [In future references I shall 

 use the numbers X. and XI. to signify the above volumes.] 



* Owen's ' Palaeontology,' 8vo, 2nd ed. (1861) p. 432. 



t X. p. 354 ; XI. p. 438. 



X E. g. Mr. Boyd Dawkins, F.R.S., in Quarterly Journal of the Geological Society of London, vol. xx. 1864, 

 p. 412 ; Mr. Gerard Krefft, " On the Dentition of Thflacoleo carnifex, Owen," Annals and Magazine of Natural 

 History, 3rd series, vol. xviii. 1866, p. 148 ; Professor W. H. Flower, F.R.S., " On the Affinities and probable 

 Habits of the extinct Australian Marsupial, Thjlacoleo carnifex, Owen," in Quarterly Journal of the Geological 

 Society of London, March 1868, vol. xxiv. p. 307. [This volume and paper I shall refer to as No. XII.] 



