1870.) MYOLOGY OF CHAMZLEON PARSONII. 887 
Interossei. Those in the pes are substantially similar to those of 
the manus. 
APPENDICULAR NERVES. 
The brachial plexus seems to be formed by three spinal nerves, 
and gives off the subscapular nerve from its posterior part. There 
is one great limb-nerve, which includes both the median and the 
ulnar nerves in it. 
The median. This great nerve perforates the coraco-brachialis 
(i. e. passes between the long and the short coraco-brachialis), and 
runs down between the postero-internal border of the brachialis 
anticus and the inner part of the triceps. At the bend of the elbow 
it perforates the pronator teres, and dipping down continues on 
between the last-named muscle and the flexor carpi radialis, the pro- 
nator accessorius, and the upper and larger condyloid belly of the 
flexor longus pollicis. 
The ulnar nerve accompanies the median till it has perforated the 
pronator teres, thus passing allogether in front of the elbow-joint. 
Then, leaving the median, it dips down between the pronator acces- 
sorius and the large inner condyloid head of the flexor longus 
pollicis. It continues along on the surface of the last-named 
muscle, and at the wrist is superficial to its tendon, but covered by 
the flexor ulnaris. It passes to the palm in the region of the fifth 
digit. 
The posterior interosseous nerve quits the median a little below 
the spot where the ulnar nerve leaves it. Passing down between the 
radius and the head of the pronator accessorius, it runs down the 
extensor surface of the arm upon the pronator quadratus, and 
covered by the extensor ossis metacarpi pollicis. It supplies the exten- 
sores metacarporum, 
The lumbar plexus is formed of two spinal nerves, as also is the 
sacral plexus. A short lumbo-sacral nerve connects the poste- 
rior root of the lumbar plexus with the anterior root of the sacral 
plexus. 
The anterior crural nerve is formed by the union of the two 
lumbar nerves, and descends in front of the anterior margin of the 
ilium at the outer border of the iliacus, which is supplied by a branch 
from it. 
The great sciatic nerve, formed by the union of the two sacral 
nerves, passes out very near to the anterior crural, being only sepa- 
rated from it by the breadth of the ilium. Covered by the ilio- 
peroneal, it passes down between the adductor and the biceps. A 
large branch is given off which is covered by the femoro-caudal, and 
passes round the head of the femur to near the origins of the semi- 
tendinosus and semimembranosus. 
The posterior tibial nerve, the continuation of the great sciatic, 
dips down between the peroneus and the flexor longus digitorum. 
It then crosses to the inner side of the leg beneath the gastrocnemius 
externus, 
Proc. Zoox. Soc.—!870, No. LIX. 
