REPORT ON THE MARSUPIALIA. 147 



and opponens of the minimus ; (2) the flexor brevis liallucis, which receives its twigs from 

 the internal plantar ; and (3) the abductor hallucis, which is supplied by the nerve to 

 the hallux. 



External popliteal (PL V. fig. 3, l). — In Thylacinus this nerve gives off no branches 

 in the thigh, but diverging outwards pierces the outer head of the gastrocnemius, and at 

 once divides into its superficial and deep portions, i.e., the musculocutaneous and 

 anterior tibial. 



The musculo-cutaneous, unlike the corresponding nerve in Man, is intended for 

 the supply of skin alone. It proceeds downwards upon the anterior aspect of the 

 leg, dispensing filaments as it goes, and ultimately it reaches the dorsum of the 

 foot where it ends in four branches, which have the following distribution: — (1) the 

 first (counting from the inner margin of the foot) constitutes the tibial branch upon 

 the dorsal aspect of the index ; (2) the second joins the fibular dorsal branch of the 

 index, which is derived from the anterior tibial ; (3) the third joins the fibular dor- 

 sal branch of the medius, which also comes from the anterior tibial ; (4) whilst the 

 fourth bifurcates to supply the adjacent margins of the minimus and annularis (PL VI. 

 fig. 3, 2). 



The anterior tibial nerve proceeds forwards between the two heads of the peroneus 

 longus, and then pierces the peroneus brevis and extensor communis digitorum to reach 

 the interval between it and the tibialis anticus. It is now continued downwards upon 

 the interosseous membrane, and, passing under cover of the upper annular ligament, 

 reaches the dorsum of the foot. Here it ends by dividing into two dorsal digital 

 branches. These are distributed thus: — (1) the first divides to supply the adjacent 

 sides of the index and medius, whilst (2) the second bifurcates to end upon the 

 contiguous margins of the medius and annularis (PL VI. fig. 3, 1). 



Muscular branches. — Between the heads of the peroneus longus the anterior tibial 

 gives off a great number of muscular branches which go to the two heads of the peroneus 

 longus, the peroneus brevis, the extensor brevis minimi digiti, upon which the nerve lies, 

 the common extensor, and the tibialis anticus. A long slender twig also proceeds down- 

 wards to supply the two lower portions of the extensor brevis. Whilst the nerve lies 

 between the tibialis anticus and the common extensor it gives additional twigs to the 

 inner part of the latter, which might be considered as an indication that the absent 

 extensor longus hallucis is fused with the extensor communis digitorum. 



In the Cuscus the external popliteal does not pierce the outer head of the gastroc- 

 nemius. At the head of the fibula it divides into the musculo-cutaneous and anterior 

 tibial (PL V. fig. 3, 1). 



The musculo-cutaneous, in passing down the leg. supplies a few twigs to the biceps, 

 under cover of which it runs. No branches, however, are given to the peroneal muscles. 

 On the dorsum of the foot it breaks up into four branches which supply dorsal digital 



