566 FOSSIL MARSUPIAL WITH LARGE GROOVED PREMOLARS, 
impossible to split the stone without breaking either the bone or 
the teeth. 
Taking into consideration the various points of structure so far 
as known, it will be noticed that not only does the form present 
features which distinguish it from any known genus, but that in 
it we have a combination of characters which render it difficult 
to be certain whether it belongs to the Macropodidce or to the 
Phalangeridce. As regards the structure of the jaw, the affinities 
on the whole are with the latter, and as regards the teeth 
apparently with the former. The absence of any opening between 
the dental canal and the hollow on the outer side of the hinder 
part of the jaw would seem to remove the form from the Macro- 
podidce and point to its connection with the Phalangers. But 
this point cannot be of any great value, as though the opening is 
generally absent in the Phalangeridce, it is present in the genus 
Petaurus. The large grooved premolars, though much better 
developed proportionally, appear to be constructed on the same 
type as those of JEpyprymnus (Hypsiprymnus) and a type quite 
distinct from that of the Phalangers. In Trichosurus where there 
are rudimentary indications of grooves it is on the hinder part of 
the tooth, the anterior part being developed into a powerful 
smooth cusp. The molars present a somewhat archaic type. 
There is no indication of ridging as in most of the existing types, 
nor is there the simple regularity of cusps found in Petaurus. In 
the little accessory tubercles we seem to have a feature suggestive 
of the multi-tubercular molars of the Secondary Marsupials. The 
minute premolars certainly recall the similar rudimentary teeth 
in Pseudochirus, Petaurus, &c, but similar rudimentary teeth 
must also have been present in the primitive Macropodidce. 
On the whole it would seem that we have in Burramys one 
more link in the chain binding the Kangaroos and the Phalangers. 
The main links would thus be — Macropus, jEpyprymnus, Hypsi- 
prymnodon, Burramys. 
The types have been placed in the Australian Museum, Sydney. 
