OF THE SOUTHERN APTERYX. 297 



'Hbialis anticus (PI. XXXII. XXXV. 8). — This muscle is overlapped and concealed by 

 the peroneus ; it arises partly in common with that muscle, and partly by separate short 

 tendinous threads from the outer part of the head of the tibia ; it gradually becomes 

 narrower, and finally tendinous two-thirds of the way down the leg ; its strong tendon 

 glides through the oblique pulley ' in front of the distal end of the tibia, expands as it 

 passes over the ankle-joint, and is inserted into the anterior part of the proximal end of 

 the tarso-metatarsal bone, sending off a small tendinous slip to the aponeurosis covering 

 the extensor tendons of the toes, and a strong tendon (8') which joins the fibular side of 

 the tendon of the following muscle. 



Extensor longus digitorum (PI. XXXV. 9). — This lies between the tibialis anticus and 

 the front and outer facet of the tibia, from which it derives an extensive origin ; its tendon 

 commences half-way down the leg, runs along the anterior part of the bone, first under 

 the broad ligamentous band representing the anterior part of the annular ligament, then 

 through a ligamentous pulley, and inclines to the inner or tibial side of the anterior sur- 

 face of the metatarsal bone, where it expands and divides into three tendons. Of these 

 the innermost is given off first, and subdivides into two tendons, one of which goes to 

 be inserted into the base of the last phalanx of the second toe ; the other portion is prin- 

 cipally inserted into the middle toe, but also sends off" a small tendon to the inner side 

 of the proximal phalanx of the second toe. The second tendon is inserted by distinct 

 portions into the second, third and last phalanges of the middle toe. The third tendon 

 supplies the outer toe. 



Extensor brevis digitorum (Pi. XXXV. 10). — A small extensor muscle arises from the 

 insertion of the tibialis anticus, and sends its tendon to the outer side of that of the great 

 extensor digitorum. 



Extensor pollicis brevis (PI. XXXV. 11). — An extensor of the small innermost toe 

 arises from the upper and inner side of the tarso-metatarsal bone. 



Peroneus medius, Cuv., Accessorius Jlexoris digitorum, Vicq. d'Azyr (PI. XXXII. XXXV. 

 12). — This strong penniform muscle arises fleshy from nearly the whole of the outer sur- 

 face of the fibula, also from the posterior part of the tibia and the interosseous space ; the 

 tendon of the biceps perforates its upper part in passing to its insertion. It ends in a 

 strong flat tendon at the lower third of the leg, which tendon runs through a particular 

 sheath at the back part of tiie tarsal pulley, becomes thickened and expanded as it ad- 

 vances forwards beneath the tarsus, joins the tendon of the flexor perforatus (1), and 

 forms with it the expansion which finally divides into three strong perforating tendons, 

 which bend the last joints of the three long toes. 



In the outer, or fourth toe, both the perforans and perforatus tendons are confined by 

 a double annular ligament ; the exterior one being continued from the adjoining toe, the 

 inner and stronger one from the sides of the proximal phalanx of the outer toe. 



' This is ossified in the Bustard and most true Gralla. 



