131 



" foramen mentale," the anterior boundary of the depression for the insertion of the 

 large temporal muscle, and the form of [symphysis closely resemble all these characters 

 as shown by the cast of the mandible first described. Mr. Krefft has dotted the depth 

 to which the socket of the lower incisive tusk descends in the symphysial part of the 

 jaw (ib.fig. 6, ?'): it is somewhat greater than that of the upper tusk. 



The length of the dental series of the upper jaw, in a straight line, is 4 inches 3 lines ; 

 that of the lower jaw is 3 inches 3 lines. 



From present data the probable formula of TJiylacoleo is : — i c p m i=i = 24. 

 Of the incisors of the upper jaw, the first is a large tusk ; of the premolars, the first is 

 small, probably two-fanged, the second a very large carnassial. The first molar is small 

 and two-fanged in both jaws, the second is restricted to the lower jaw, is still smaller, and 

 is single-rooted. 



Besides the full confirmation which the additional fossils, here described, give of the 

 marsupiality of TJiylacoleo, its closer affinities in that Order are shown to be, not to the 

 existing Carnivorous Marsupials, e. g., Sarcophilus, Dasyurus, TJiylacinus, Didelphys, 

 but to the Diprotodons, Nototheres, Koalas, Phalangers, and Kangaroos. It may, I 

 think, be said that the skull above described is one of the most singular and interesting 

 mammalian fossils hitherto discovered. 



Admeasurements of the Skull. 



in. lin. 



Length 9 8 



Length of the facial part anterior to the orbit 3 



Breadth at the preserved posterior part of the zygoma 7 2 



Breadth at the preserved anterior root of the zygoma 6 9 



Breadth of the cranium between the temporal fossae 2 3 



Length of the bony palate, from the fore border of the palato-nares . . . 2 11 



Breadth of the bony palate at the same part 3 6 



From the fore end of premaxillary to the hind border of the palato-nares . 4 9 



From the hind border of the palato-nares to that of the occipital condyles . 5 6 



Length of the temporal fossa, including the orbit 7 2 



Breadth of the interorbital space across the antero-superorbital ridges . . 3 10 

 Breadth of the interorbital space behind the antero-superorbital ridges ..30 



Least breadth of the foramen magnum . Oil 



Least height of the foramen magnum 7 



Breadth between the upper ends of the condyles 14 



Breadth across the broadest part of the condyles 2 5 



Breadth across the paroccipitals 4 2 



Breadth across the mastoids 5 3 



Vertical diameter, or depth of the upper jaw, at and including the fore part 



of the camassial tooth .... 40 



4 



