504 ANATOMY OF VERTEBRATES. 



not by the petrosal and tympanic, as in the Dog. The tympanic 

 has preserved its distinctness in the Thylacine, but has coalesced 

 with other elements of the temporal bone in the Dog. A wide 

 and deep groove divides the bulla from the basisphenoid in the 

 Thylacine, but the sides of the basisphenoid in the Dingo are 

 swollen and abut against the large tympanic bullas. The arti- 

 cular cavities for the lower jaw are much nearer the occiput in 

 the Thylacine than in the Dingo, and the malar bones enter 

 partially into their formation. There are two large vacuities in 

 the back part of the bony palate in the Thylacine, but this part 

 is entire in the Dingo. The antorbital foramina are larger in the 

 Thylacine, and much nearer the orbits than in the Dingo ; they 

 are also formed partly by the malar, and are not wholly per- 

 forated in the maxillary bone, as in the Dingo : the lacrymal 

 bone is much larger in the Dingo, and encroaches much more 

 upon the face : the nasal bones are broader posteriorly in the 

 Dingo, and extend further back, as compared with the maxillaries. 

 The petrosals are much larger in the Dingo, and send bony plates 

 into the tentorium, which plates are not present in the Thylacine. 

 The chief bony part of the tentorium projects from near the 

 middle of the occiput, and does not reach the petrosal in the 

 wild Dog. The sella turcica is defined by the posterior clinoid 

 processes in the Dingo, but not in the Thylacine. The foramina 

 optica and lacera anteriora are blended together in the Thylacine, 

 but are distinct in the Dog. Although the olfactory chamber is 

 so much larger in the Thylacine, the rhinencephalic fossa is 

 smaller than in the Dog. The lower jaw, besides its greater 

 length and slenderness in the Thylacine, differs by the bending in 

 of the angle, which is the characteristic of the Marsupials. In 

 most of these distinctions the Thylacine manifests its nearer 

 affinity to the oviparous type of skeleton. 



The chief distinction between the wild and domestic Doofs is 

 the greater proportional size of the cranium to the face in the 

 latter, and this increases as the size of the variety diminishes. 



The affinity of the Hytena to the Viverridce is shown, in the 

 skull, by the broad, triangular, rough plate formed by the paroc- 

 cipital and mastoid, and applied to the back part of the acoustic 

 bulla: but the pterygoid processes are not pierced by the ecto- 

 carotids. The strength of the muscles which work the jaw is 

 shown by the extent of the temporal fossae, the height of the 

 sagittal crest, the thickness and the expanse of the zygomatic 

 arches, the height of the coronoid processes, and the depth of the 

 strongly-defined fossa3 into which the great muscles of mastication 



