o/Bradypus tridactylii.^. 65 



The liip-joint is strengthened by three ligaments — a capsular, 

 an ilio-fenioral accessory, and a cotyloid ligament 5 but there is 

 no ligamentum teres. 



The muscles of the leg are : — 



Tibialis anticus, which arises from the tihla and from a 

 small ])art of the iibula about its middle, and is inserted by 

 an undivided tendon into the middle of the base of the inner 

 metatarsal bone; its fibular head is very diminutive. In 

 Orycteropus it rises higher, to the ligamentum patellar, and its 

 tendon is split into two slips. Meckel mentions two separate 

 origins in the Ai; but the tibial and fibular origins are not really 

 separate. The Armadillo has but one head and one tendon ; 

 the Anteater luis one tendon and two heads (Meckel). 



Extensor digitorum longus arises nornudly from the heads 

 of the tibia and fibula, and its origin is prolonged upwards to 

 the femur ; it ends in a weak tendon, which is inserted into 

 the second metatarsal bone and into the dorsal aponeurosis of 

 the digit. This peculiarity of insertion was noticed by Meckel, 

 but its femoral origin was not. In the Orycterope the femoral 

 origin exists, and its tendiins are traceable to the toes. In 

 Dasyjms there is no condyloid head. Cuvier notices very 

 accurately that in many of the Edentates this muscle has a 

 femoral head. 



Extensor hallucis proprius arises from the fibula and Interos- 

 seous membrane and is inserted into the first phalanx of the 

 first toe. It, like the preceding, is very small. 



Extensor brevis digitorum arises from the lower extremity of 

 the fibula and tibia, and is inserted into the first phalanx of 

 the inner toe. This muscle is larger than the last, though 

 short. 



Peroneus longus arises from the outer condyle of the femur 

 and from the upper part of the fil)ula ; it passes doAvnwards 

 behind the outer malleolus, and is inserted into the outer meta- 

 tarsal bone. In theOrycterojje and Armadillo its tendon crosses 

 the sole as it does in man. In the Anteater one of the peronei 

 tendons closely resembles this. 



Peroneus brevis arises as usual from the lower two-thirds of 

 the outer side of the fibula. It is quite separate from the 

 peroneus quinti, which runs along its posterior border and has 

 its usual insertion into the outer metatarsal bone. 



No peroneus quartus was ])resent, nor any peroneo-calcanean 

 muscle. The former exists in the Orycterope (Galton, p. 598). 

 Peroneus quinti is distinct in the Armadillo, 



Gastrocnemius arises by three heads, which are separate for 

 their whole length. The two femoral heads arise from the pos- 

 terior surface of either condyle, and are inserted into the calca- 



Ami. & Mag, N. Hist. Her. 4. Vol. iv. 5 



