550 ALLIS. [Vor. XII. 
diately dorsal to the origin of the levator arcus palatini, the sur- 
face of origin of which muscle extends a little in front of it. 
The muscle lies on the inner surface of Az, does not come to 
the level of the outer surface in any part, is nearly vertical in 
position, and the fibres of 42" run downward and forward across 
it at a considerable angle. Its fibres, which are all inserted 
along the upper, anterior edge of the tendon, or fascia, on the 
inner surface of Az, are long in front and short behind where 
they gradually vanish, the fascia here extending upward to the 
origin of the muscle. At this point A2” begins, arising as a 
thin sheet, partly tendinous in front and wholly so behind, where 
it lies superficial to the dilatator operculi. This fascia, rather 
than muscle, is attached in front to the upper, outer edge of the 
cartilaginous rib that forms the lateral boundary of the anterior 
diverticulum of the temporal groove, which rib is, in the adult, 
inclosed in a V-shaped process on the under surface and outer 
edge of the squamosal (No. 104, p. 188). As this V-shaped 
process has not, at this age, begun to form anteriorly, the origin 
of the fascia in that part is entirely from the cartilage. Poste- 
riorly, where the process is represented by a single bony fin or 
plate along the outer edge of the squamosal, the line of origin 
of the fascia extends onto that fin, that is, onto the lateral edge 
of the squamosal. In the adult this fascia has become muscu- 
lar, and the surface of origin of the muscle is a narrow line 
extending along the outer edge, and along the under surface of 
the squamosal, back as far as the upper end of the preopercu- 
lum. This uppermost portion of the muscle is in the adult thin 
and partly tendinous. It lies immediately superficial to the 
levator arcus palatini and dilatator operculi, and passes almost 
abruptly, at the lower edge of the dilatator, into the thick fleshy 
lower portion of the muscle. 
The inner, deeper division of the adductor, A3, lies imme- 
diately underneath Az. Although a relatively small muscle, it 
has a large surface of origin, arising from the hyomandibular 
below the external opening of the facial canal, from the outer 
surface of the quadrate down to the articular swelling at its dis- 
tal end, from the outer surface of that part of the metaptery- 
goid that lies behind the front edge of its median, dorsal pro- 
