THE MUSCLES OF THE LOWER EXTREMITY. 233 



metatarsal bone. It winds round to the inner side 

 of this, fits snugly in its groove beneath, then passes 

 along on the under side of the shaft of the basal joint 

 of hallux, to become filially inserted into the tubercle 

 at the inferior proximal end of its ungual phalanx. 



This muscle is a powerful flexor of the hind toe or 

 hallux. When it contracts, however, it also acts upon 

 other flexors of the toes, soon to be alluded to, so there 

 is not absolute independence of action here. 1 



1 Of the flexor perforatus indicia secundus pedis and the flexor 

 longus hallucis, as they occur in Geococcyx calif or nianus, I have said 

 that : 



' The flexor perforatus indicts secundus pedis (Fig. 63 bis] is 

 even a better developed muscle than I found it to be among typical 

 Corvidse, some of which I have recently dissected, and it is fully 

 as well individualized. 



" It arises from the fascia at the outer side of the knee-joint, and 

 from the contiguous surface of the external condyle of the femur. 

 Here it receives the anastomosing fibres of the extremity of the 

 tendon of the ambiens. 



" The muscle is fusiform in shape and accurately moulded on the 

 flexor it covers at its side. Its tendon in descending the leg is thin 

 and ribbon-like. At the ankle it passes through the tibial cartilage, 

 and crossing the joint goes through, with the second tier of tendons, 

 the cartilaginous cap on the back of the hypotarsus of the tarso- 

 metatarsus. Passing down behind this latter bone, and through the 

 annular ligament in the sole of the foot, it proceeds to the under side 

 of the second toe, beneath the second phalanx of which it expands to 

 form a tubular sheath for the passage of the deep flexor, while at 

 the same time it becomes attached to the side of this joint of the toe 

 in question. 



" The carneous portion of this muscle in the leg is to the outer side 

 of the loop for the biceps flexor crucis, and, owing to the fact that it 

 varies in form and size in different birds, it is as well to bear this in 

 mind. 



" The flexor longus hallucis (Fig. 64 bis) has two separate heads, 

 the one coming off from the outer side of the external condyle of the 

 femur, and the other, far more fleshy, arising from the posterior 

 aspect of the same bone between the condyles. Above, this muscle 



