710 MR. F. G. PARSONS ON THE [June 16, 
by Paterson as derived from the dorsal divisions of the plexus, 
the median as derived from the ventral. In all the animals 
dissected by Paterson, and in all that I have hitherto dissected, 
the radial nerve came from the musculo-spiral; in this case, 
however, the radial rose on both sides from the median, although 
no connection between that nerve and the dorsal roots was observed 
in the plexus. 
The arrangement of the Lumbar Plexus of the Rock-Kangaroo 
closely resembles that of the Cuscus described by Cunningham’; 
it is formed by the 2nd, 3rd, 4th, and a large part of the 5th 
lumbar nerves, the 1st lumbar being distributed to the abdominal 
walls. 
The genito-crural nerve is very small and rises from the 2nd 
and 3rd lumbar, whence it runs down to supply the cremaster, no 
crural branch being seen. 
The anterior crural comes from the 3rd, 4th, and 5th lumbars, 
and emerges from the outer surface of the psoas, soon after which 
it gives off the external cutaneous to supply the skin of the outer 
side of the thigh. As soon as the nerve has passed under 
Poupart’s ligament it gives off a cutaneous branch to the skin of 
the front and inner side of the thigh. Soon after this a branch 
runs outwards to supply the sartorivs, and from this a twig enters 
the superficial surface of the rectus femoris. The next branch is 
the long saphenous which comes off from the inner side of the 
nerve, passes superficial to the external circumflex artery, and 
supplies the skin on the inner side of the leg below the knee. 
The rest of the branches of the anterior crural pass deep to the 
external circumflex artery and supply the quadriceps extensor set 
of muscles. The obturator nerve comes from the anterior divisions 
of the 4th and 5th lumbar, passes to the obturator foramen, and 
divides into a brush of branches which supply the adductor 
muscles as well as the gracilis. No distinct division into super- 
ficial and deep parts was noticed. 
In the plexus, branches to the psoas come from the 2nd and 
3rd as well as the junction between the 4th and 5th lumbar 
nerves. 
The Sacral Pleaus is formed by the 5th and 6th lumbar and the 
greater part of the first sacral nerves, which all unite to form the 
main trunk of the great sciatic. From the junction of the 5th 
and 6th lumbar nerves the superior gluteal is given off, as is the 
case in the sacral plexus of the Cuscus; this nerve supplies the 
gluteus medius, minimus, and quartus. The inferior gluteal 
comes off in common with the small sciatic after the union of the 
1st sacral with the cord formed by the 5th and 6th lumbar (lumbo- 
sacral cord) ; it supplies the gluteus maximus and the anterior part 
of the biceps. The small sciatic supplies the skin of the back of 
the thigh as usual. 
The pudic nerve is formed by the part of the Ist sacral which 
1 Journ, Anat. vol. xv. p. 265. 
