MAMMAL-LIKE REPTILES, 757 
this process forms a floor to the anterior part of the nasal cavity, 
and its outer border is in contact with the septomaxilla. The 
outer side of the premaxilla has a powerful articulation with 
the maxilla, In R. 3594 the facial part of the bone is continued 
upwards by a long and slender internarial process which separates 
the nasals for a great distance. 
Text-figure 6. 
Pnigalion oweni. Type-skull, dorsal aspect, X 2. 
The maxilla (Mx.) is a bone with few remarkable features; in 
front it joins the premaxilla, and thence backwards forms a 
large area of the face. It is completely excluded from the border 
of the external naris by the septomaxilla, with which in R. 3594 it 
has a long suture. In this specimen it then has a short contact 
with the nasal and is finally terminated by sutures with the 
lachrymal and jugal. On the palate the maxilla is only repre- 
sented by its wide tooth-bearing edge and forms part of the 
border of the choana; for the rest of its length it is in contact 
with the palatine and transverse bones. 
The septomaxilla (S.Mx.) is a variable bone in Tapinocepha- 
loids. In R. 3594 it has an internarial part which unites by 
suture with the premaxilla to form a floor to the nasal cavity ; 
it then sends back a large facial part which forms the whole of 
the posterior border of the nostril and separates the nasal and 
