MYOLOGY OF OPISTHOCOMUS CEISTATUS. 365 



from the whole length of the outer side of the shaft of the proximal phalanx, and is 

 inserted into the external surface of the base of the distal phalanx. This muscle 

 abducts the first digit, and draws it across the plantar aspect of the second. 



The articulation between the first metatarsal and its phalanx is of the nature of an 

 enarthrodial joint, the head being proximal, and the cavity distal. The bones are con- 

 nected by a capsular and a strong ligamentum teres. 



The gastrocnemius, plantaris, and popliteus present their usual arrangement. 



The analogue of the soleus consist of a series of differentiated muscular slips. The 

 most external of the series arises from the outer tuberosity of the tibia, and from nearly 

 the whole length of the shaft of the fibula. It terminates in a long slender tendon, 

 which grooves the ankle-joint, and traverses the plantar aspect of the foot as far as the 

 1st phalanx of the 3rd digit, where it splits into two tendons to allow of the passage of 

 the deepest flexor tendon. It is finally inserted into the sides of the 2nd phalanx of the 

 same digit. This is the perforans portion of the soleus series to the 3rd digit. 



The perforatus portion to the same digit arises tendinous from the back of the lower 

 end of the femur. It terminates in a strong tendon which grooves the lower end of the 

 tibia, traverses the plantar surface of the foot, and divides opposite the distal end of 

 the metatarsal bone to permit the passage of the tendon of the perforans (preceding 

 tendon). The two minor tendons are inserted into the sides of the 1st phalanx of the 

 3rd digit. 



The next muscle of the series is situated on a deeper plane. It arises from the 

 external condyle of the femur, and from the adjacent portion of the head of the tibia. 

 It is inserted into the sides of the base of the 1st phalanx of the 4th toe, its tendon 

 previously splitting to allow the passage of the perforans tendon. The latter springs 

 from a muscular belly, which arises in conjunction with the former. On a still deeper 

 plane is another segment, which sends a tendon to the sides of the 1st phalanx of the 

 2nd digit. There is still another segment, which, by its tendon, joins the long flexor 

 tendon on its tibial side in the plantar region. 



The flexor longus hallucis and tibialis iwsticus are represented by two small muscles ; 

 one arises from the outer half of the upper third of the tibia. It soon ends in a strong 

 tendon, which is inserted into the proximal end of a large pulley-like sesamoid bone, 

 which plays over the posterior aspect of the ankle-joint. The other, about half an inch 

 above the ankle-joint, joins the preceding as a small muscle, which springs from the 

 lower end of the fibula. 



The_^e^or longus digitorum is a large and fleshy muscle. It is attached proximally 

 to the upper half of the posterior surface of the tibia, and fibula nearly its whole length. 

 It is bipenniform in shape ; its muscular fibres extend as far as the ankle-joint, resulting 

 in a strong tendon, which passes behind and between the two sesamoid bones covering 

 the joint. It then passes between the two metatarsals and through a distinct osseous 

 canal into the plantar region, where it divides into four tendons, previously receiving, 



