19 
Balena antarctica, and of the Myrmecobius, 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 Phascolothertum—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 Mr. 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- 
vexity 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 well as with the placental zoo- 
phaga. The general form and proportions of the coronoid process 
closely resemble those in zoophagous marsupials ; but in the depth 
and form of the entering notch, between the process and the condyle, 
it corresponds 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 difference is not one which approximates the fossil in question 
to any of the placental zoophaga; on the contrary, it is m 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, differs from all zoophagous 
marsupials, and the placental fere ; but in the Hypsiprymnus 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 resembles the symphysis of the Dzdelphys 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; 
but in their scattered arrangement they resemble the incisors of the 
Myrmecobius. In the relative extent of the alveolar ridge occupied by 
the grinders, and in the proportions of the grinders to each other, espe- 
cially the small size of the hindermost molar; the Phascolothere resem- 
bles the Myrmecobius more than it does the Opossum, Dasyurus or 
Thylacynus ; but in the form of the crown, the molars of the fossil re- 
semble the Thylacynus more closely than any other genus of marsupials. 
In the number of the grinders the Phascolothere resembles the Opossum 
and Thylacine, having four true and three false in each maxillary 
c2 
