xiii.] MARSUPIALIA, 237 



bones resemble generally in their extent and disposition 

 those of the Dog. 



Externally the conformation of the zygomata, temporal 

 fossae, orbits, maxillae, premaxillae, and nasals are strikingly 

 similar to those of the Dog ; but the lacrymal bone of the 

 Thylacine is larger both within and without the orbit, and 

 it has one perforation within, and either one or two just 

 external to the margin of the orbit. The palate has a pair 

 of large oval vacuities between the molar teeth. The ptery- 

 goid plates are very thin. The glenoid fossa is rather more 

 expanded from before backwards than in the Dog, and the 

 malar extends so far back beneath the zygomatic process of 

 the squamosal as to form the outer edge of the glenoid cavity. 

 The postglenoid and paroccipital processes are developed 

 much as in the dog ; the former has rather greater lateral 

 extent. A great difference is seen in the condition of the 

 tympanic, which in the Thylacine is quite rudimentary, forms 

 no bulla, and is not ankylosed to the other cranial bones, 

 so that in the dried skull it is nearly always detached. On 

 the other hand, the hinder part of the alisphenoid is dilated 

 into an oval thin-walled capsule, which is connected with 

 the front of the tympanic cavity. The periotic is not 

 ankylosed to the squamosal, has a very large floccular fossa 

 within, and a mastoid portion forming a long, narrow strip 

 visible in the outer side of the occipital surface of the skull, 

 between the squamosal and the exoccipital, almost exactly 

 as in the Dog. The exoccipital is perforated by the con- 

 dylar foramen ; but the carotid foramen, instead of passing 

 through the inner edge of the tympanic bulla, perforates 

 the basisphenoid, passing very obliquely forwards and in- 

 wards. The large alisphenoid is pierced by the fora- 

 men ovale near its posterior margin, and by the foramen 

 rotundum near the front. The orbitosphenoid is very small, 



