478 O. CHARNOCK BRADLEY, 
deeper portion of Varanus only; since in Gecko it arises from the 
columella only, and in Agama from this bone and slightly from the 
membranous cranium in its vicinity. 
It is perhaps noteworthy that in Varanus and Pseudopus this 
muscle has a double nerve supply; or to be more precise, there are 
two distinct nerves passing to its superficial portion. One of these 
is small and arises from that branch of the N. mandibularis which 
pierces the M. capiti-mandibularis to supply the skin of the cheek 
and the M. levator anguli oris (Fig. 2 B). The other nerve arises 
in common with that which supplies the M. pterygo-mandibularis 
(Fig. 3 C). It pierces the deeper portion of the M. pterygoideus — 
supplying branches en route — and terminates in the superficial portion. 
M. pterygo-mandibubularis (Fig. 1 M.ptery-mand). 
This is a powerful muscle, and apparently very uniform in its 
attachments in the Lacertilia. Its origin in Varanus is from the 
outer surface of the whole of the pterygoid bone except that branch 
which passes forwards to articulate with the palatine. The most 
anterior part of its origin is somewhat tendinous; the rest is fleshy. 
Its insertion is into the Os angulare, the strongest attachment being 
to the projecting posterior extremity of this bone. The tendinous 
origin is very well marked in Agama; and, from the observations of 
SANDERS, also in Platydactylus and Liolepis. This peculiarity is ap- 
‘parently of some moment as it corresponds to the double origin of 
the homologous muscle as described by D’ALTON (10) in Python 
bivittatus. 
When the Mm. capiti-mandibularis and pterygoideus have been 
removed, three deep muscles are revealed. Their extent and dispo- 
sition are more fully demonstrated by the removal of the quadrate and 
columella, and the depression of the corresponding half of the mandible. 
These muscles differ from those already described inasmuch as they 
have no connection with the mandible. They run between the cranium 
and the pterygo-palatine arch and are arranged as follows. 
M. pterygo-sphenoidalis posterior (Figs. 3 and 4 
M. pt. sph.-post). 
This is a triangular muscle arising by its apex from that part of 
the basisphenoid which forms the lower boundary of a notch whose 
upper limit is established by the prootic bone and into which the 
Gasserian ganglion projects. From this comparatively circumscribed 
