OF THE SOUTHERN APTERYX. 295 



The gastrocnemius internus (PI. XXXV. r) has two powerful heads, one from the femur, 

 the other from the tibia; the first (r)' arises fleshy from the internal condyle of the 

 femur, expands as it descends, and receives additional fibres from the lower edge of the 

 accessorius semitendinosi. About one-fifth down the tibia this muscular origin in the 

 right leg terminated in a flattened tendon (r*), which became attached to the inner 

 side of the tibial portion of the gastrocnemius internus (r**). In the left leg the tendon 

 soon divided ; one portion passed to the soleus, the other went to join the tibial portion 

 of the gastrocnemius internus. The second head, which is separated from the precedin" 

 by the insertion of the semitendinosus, arises partly from the internal and anterior part 

 of the strong fascia of the knee-joint by short tendinous fibres, which almost immediately 

 become fleshy, and partly from a well-defined triangular surface (r**) on the inner and 

 anterior aspect of the head of the tibia : the fleshy fibres converge, receive the tendinous 

 slip from the femoral portion, and end on the inner side of the muscle in a strong flat- 

 tened tendon, about two-thirds down the leg : this joins the tendon of the gastrocnemius 

 externus (Re), and is inserted as described above. 



Soleus^ (PI. XXXV. s). — This is a slender flattened muscle arising from the posterior 

 part of the head of the tibia, the tendon of which joins that of the gastrocnemius internus, 

 behind the tarsal joint. 



The Flexor perforans digitorum (PI. XXXI. XXXII. XXXV. 1) lies immediately anterior 

 to the external gastrocnemius ; it arises fleshy from the outer condyle of the femur, below 

 the tendinous origin of that muscle, and terminates in a slender flat tendon half-way down 

 the leg. Its tendon (1) glides behind the tarsal joint through the sheath of the gastro- 

 cnemius, expands beneath the metatarsus and bifurcates, sending its smallest division to 

 the inner toe, and its larger one to blend with the tendon of the peroneus medius (12). 



Flexor perforatus of the outer toe (PI. XXXI. XXXII. XXXV. 2) .—This arises by very 

 short tendons from the proximal end of the fibula, and from the ligament forming the 

 bicipital pulley ; it continues to derive a thin stratum of fleshy fibres from the fascia cover- 

 ing the anterior surface of the muscles of the leg : the fleshy fibres terminate half-way down 

 the leg in a flattened tendon, which, after entering the gastrocnemial sheath, pierces the 

 tendon of the first perforatus of the middle toe, then runs forward to the outer toe, ex- 

 pands into a thick ligamentous substance beneath the proximal phalanx, and sends off" 

 two tendinous attachments on each side, one to the proximal, the other to the second 

 phalanx, and is continued to be finally inserted into both sides of the third phalanx. 



Flexor perforatus digitorum (PI. XXXII. XXXV. 3, 4, 5, 6) is the strongest of the three ; 

 it arises fleshy from the posterior part of the distal extremity of the femur, above the 

 external condyle (PI. XXXII. 4), and also by a distinct flattened tendon (6), one inch in 



' This is described as the solevn in the Cassowarj^, by Prof. Mayer, loc. cit. p. 15, but the origin of this muscle 

 is not extended in other animals above the knee-joint. 



' This is described as the plantaris in the Cassowary, by Prof. Mayer, loc. cit. p. 14, but the normal origin of 

 that muscle should be sought for above the knee-joint. 



2r2 



