222 Geological Society. 



chylosed at one part, and the ligaments of connexion attached at the 

 other. The form, depth and position of the sockets of the teeth in 

 the ThyJacothere are precisely similar to those in the small opos- 

 sums. The colour of the fossils, Mr. 0-^-en said, could be no ob- 

 jection to those acquainted with the diversity in this respect, which 

 obtains in the fossil remains of Mammalia. Lastly, with respect to 

 the Thylacothere, the author stated, that the only trace of compound 

 structure is a mere vascular groove running along its lower margin, 

 and that a similar structure is present in the corresponding part of 

 the lower jaw of some species of opossum, of the Wombat, of the 

 Baleena antarctica, and of the Myrmecobiits, though the groove does 

 not reach so far forwards in this animal ; and that a similar groove 

 is present near the lower margin, but on the outer side of the jaw, 

 in the Sorex Indicus. 



Description of the Half Jaw of the Phascolotherium — This fossil 

 is a right ramus of the lower jaw, having its internal or mesial sur- 

 face exposed. It once formed the chief ornament of the private 

 collection of ]\lr. Broderip, by whom it has since been liberally pre- 

 sented to the British Museum. It was described by Mr. Broderip 

 in the Zoological Journal, and its distinction from the Thylacothe- 

 rium clearly pointed out. The condyle of the jaw is entire, stand- 

 ing in bold relief, and presents the same form and degree of con- 

 vexitj' as in the genera Didelphys and Dasyurus. In its being on a 

 level with the molar teeth, it corresponds with the marsupial 

 genera Dasyurus and Thylacynus as weU as with the placental zoo- 

 phaga. The general form and proportions of the coronoid process 

 closely resemble those in zoophagous marsupials ; but in the dejjth 

 and form of the entering notch, between the process and tlie condyle, 

 it coiTesponds most closely with the Thylacynus. Judging from the 

 fractured surface of the inwardly reflected angle, that part had an 

 extended oblique base, similar to the inflected angle of the Thy- 

 lacynus. In the Phascolotherium the flattened inferior surface 

 of the jaw, external to the fractured inflected angle, inclines out- 

 wards at an obtuse angle with the plane of the ascending ramus, 

 and not at an acute angle, as in the Thylacyne and Dasyurus ; but 

 this difi^erence is not one which approximates the fossil in question 

 to any of the placental zoophaga : on the contrary, it is in the 

 marsupial genus Phascolomys, where a precisely similar relation of 

 the inferior flattened base to the elevated plate of the ascending ramus 

 of the jaw is manifested. In the position of the dental foramen, 

 the Phascolothere, like the Thylacothere, difl'ers from all zoophagous 

 marsupials, and the placental yer«; but in the Hypsipryinnus and 

 Phascolomys, marsupial herbivora, the orifice of the dental canal is 

 situated, as in the Stonesfield fossils, very near the vertical line 

 dropped from the last molar teeth. The form of the symphysis, 

 in the Phascolothere, cannot be truly determined ; but Mr. Owen is 

 of opinion that it resemble."? the symphysis of the Didelphys more 

 than that of the Dasyurus or Thylacynus. 



Mr. Owen agrees with Mr. Broderip in assigning four incisors to 

 each ramus of the lower jaw of the Phascolothere, as in the Didelphys i 



