310 PEOrESSOE OWEN ON THE FOSSIL MAMMALS OF AUSTEALIA. 



" Bona Vista, New Melbourne, 25 January 1816. 



" My deak SiE, — I send you, by Captain Buerell of the ' Achilles,' a box which 

 contains some interesting fossil bones, from a lake eighty miles south-west of Melbourne. 

 They were discovered and kindly forwarded to me by Mr. W. Adeney, who has a sheep- 

 station on the banks of the lake. I have since visited the lake, which is called by the 

 aborigines ' Colungoolac' It is very shallow, indeed almost dry in autumn, its muddy 

 bottom being covered with a pretty thick deposit of common salt of excellent quality. 

 This is the case in most of those in this -part of Australia. The whole of this part of the 

 country is volcanic, and probably these salt lakes are the deeper parts of the ancient sea. 

 There is one, however, called ' Parrumbat,' which appears to be the crater of an extinct 

 ^■olcano. Its waters are from eighteen to twenty fathoms deep, Avith abrupt and almost 

 perpendicular escarpments, except at two points, which appear to have been the outlets 

 to streams of lava. The sides are regularly stratified, and consist apparently of con- 

 densed scorise. The strata are singularly undisturbed and perfectly parallel, except in 

 those places where large globular pieces of compact lava have fallen, and here their 



direction has been altered, as indicated in this rough diagram. 



As these are some of the features of the country in which these ^^"^^^^ 

 bones are found, I think, perhaps, it may not be uninteresting to mention them. The 

 fragment of skull and incisor I hope may be new to you. 



" I sent you about a year ago a box of the Mount Macedon fossils, by Captain 

 Fordyce of the brig 'Athens.' 



(Signed) " Henry Hobson." 



The ' skull ' consisted of the cranial part (Plates XL XIII. and XV. fig. 1), similar in 

 size and in the development of the temporal ridges and fossse to that of a Lion. The 

 ' incisor ' was a large tooth with a trenchant or incisive crown, implanted, with a small 

 tubercular tooth, in a portion of the right superior maxillary bone, including part of 

 the orbit and lacrymal bone (Plate XL fig. 1,^ 4, and fig. 2). 



The latter specimen gave decisive confirmation of the carnivorous character of the 

 fossil, the 'incisor' tooth (p answering in shape and function to the great sectorial or 

 ' carnassial ' (Plate XV. fig. 4, ^ 4), and the tubercular tooth (fig. 1, vi 1) to the small 

 tubercular molar (fig. 4, mi) of the Lion*; being situated, as in that animal, on the 

 inner side of the back part of the sectorial tooth. Fortunately the nasal process of the 

 maxillary in the detached facial portion of the skull of the Thylacoleo fitted a sm-face at 

 the fore-part of the cranium in such a way as to demonstrate that it formed part of the 

 same skull, completing the lower half of the orbit (Plate XL fig. 1, 0'), of wliich the 

 upper half (0) remains in the cranial portion of the skull. 



* The real homologiea of tliese teeth can only bo detertnincd by specimeua of young Thijlacoleo, show- 

 ing the order of development and change of the dentition : the symbols here only indicate the conformity of 

 general 8hap(> and function to p 4 and in 1 in Felis. 



