244 
MR. W. K. PARKER ON THE STRUCTURE AND 
(■ nix,.). The alveolar walls of the only upper incisor tooth are imperfect behind ; this 
tooth is often wanting in the adult, The openings for Jacobson’s organs ( j.o. ) are far 
forwards, and the palatine processes of the premaxillaries are largely hidden by those 
of the maxillaries.'" 
The maxillaries (mx.) show three parallel regions in this view : the alveolar, with 
the large tooth-sockets and teeth just appearing ; the submarginal, with oblique 
ribbings and hollows; and the sub-mesial, separated from the ribbed part by a crack, 
or sharp, roughish fissure, which looks very much like a suture. The outer part binds 
on the premaxillary, and the inner tract on its palatine process, hiding most of it. 
The submesial tract rises somewhat where it meets its fellow, so as to form a definite 
fossa; these two tracts fail behind, being aborted by the counterpart tracts of the 
palatines. 
These bones (pci.) form a very elegant winged part of the hard palate, for the 
posterior palatine foramina notch them, close behind the fissure, in the maxillary plate, 
and inside the foramen they each have a round lobe running forwards, and outside 
it another, which fits obliquely to, and extends beyond, the end of the maxillary. 
In front, these palatine plates of the palatines are hollow where they meet, and then 
this shallow fossa runs obliquely outwards on each bone, leaving the middle part 
convex. The hind margin, as a whole, is transverse, but it is deeply crenate, there 
being two notches on each side the projecting ends of the bone at the median suture. 
The orbital, or ascending, part of the palatines is steep, hollow inside, and gently 
convex outside; the hind half of each plate embraces the side of the presphenoid, 
and, slightly diverging, is joined by the small sub vertical pterygoid (pg.), which 
diverges still more, and has a nucleus of cartilage (as in the Hedgehog and Mole) on 
its hamular process. I find no trace of the mesopterygoid—a test-bone for Marsupial 
relationship. Nor does the jugal (malar— j.) come near the glenoid facet; here, 
again, this type is normally Eutherian. The squamosal (sq.) has a short, triangular 
jugal process, overlying that great bone, and behind it the concave glenoid cartilage 
has a pyriform outline and an oblique position—inwards and a little forwards, also. 
The lateral and post-glenoid part of the squamosal is rather feeble, and is bound 
upon by the tympanic ( ci.ty .) ; its processes are best seen in the side view (fig. 3); 
the hollow face of the wide orbital roof ( f.) is seen in this view, in the distance. 
The annulus (ci.ty.) is like a large capital Q with the top looking backwards; it 
gives a wide space for the membrana tympani, has a large trowel of bone on 
its front crus, and has the hind crus inturned and blunt. The cartilage of the 
Eustachian tube (eu.) is large, as in Marsupials, and as in Marsupials, behind and 
outside it, but inside the proper thick annulus, there is a thin crescentic “ os bullas ” 
# The abortive development of the single npper incisor, and the perfect condition of the hard palate, 
carry ns far away—upwards—from the Marsupial territory. These things foreshadow what will he seen 
in Bats, some Lemurs ( Lepilemur ), and, ultimately, in the Ruminants. 
