VIIL] THE MUSCLES. 



349 



fibula, or, as in the Chameleon, by a fan-like expansion into 

 the outer side of the fibula. This muscle is very generally 

 developed, as it exists even in Menobranchns, where it seems 

 to represent the long head of the biceps femoris of man. 



(2) We have sometimes (e.g. in Urodeles) a muscle 

 springing from the shaft of the femur, just below the inser- 

 tion of the femoro-caudal, and itself inserted into the fibula. 

 It seems to answer to the short head of the human biceps 

 femoris, and if so it is interesting to note at what a remote 

 distance from man we find a striking analogy to human 

 structure, which yet seems absent in the Sauropsida (Fie 

 313, B\ 



(3) We have the large and very remarkable muscle (the 

 femoro-caudal, before described) arising from the caudal 

 vertebrae, and inserted by a very strong tendon into the great 

 trochanter, but giving off a delicate tendon passing down 

 into the popliteal space to the inter-articular cartilage between 

 the femur and the tibia. 



(4) Finally, we .have in some Reptiles (e.g. the Iguana) a 

 muscle arising from the tendinous arch, which passes from 

 the so-called ilium to the so-called spine of the pubis, and 

 inserted by a tendon (passing between the tibia and fibula) 

 into the front aspect of the upper part of the tibia, or passing 

 down to a plantar ossicle, as in the Chameleon (Figs. 309, 

 312, and 317, BF\ 



By a still greater complication this muscle may be doubled, 

 as in the Crocodile and Alligator ; one part having a twofold 

 insertion into the front of the tibia and the plantaris muscle, 

 the other portion having a twofold insertion into the head of 

 the fibula and the external gastrocnemius. 



Semi-tendinosus. This is exceptionally slender in man. 

 Even in man's own order it may have a second head of origin 

 from the coccygeal vertebrae, as in the Aye-aye ; and often in 

 other Mammals (e.g. the Horse) it is very large. Its insertion, 

 even in Apes, is lower than in man and Bats. In the Dog and 

 Cat it is attached to the middle of the tibia, while in the Bear 

 it is inserted still lower. This muscle may partly end in a 

 tendon becoming confluent with that of the internal gastro- 

 cnemius, as in Birds. A muscle which may be the semi- 

 tendinosus, but which otherwise has no representative in man, 

 springs from the tendinous arch referred to in speaking of the 

 biceps, and is inserted into the upper part of the tibia by a 

 tendon common to it and to the gracilis in the Iguana, or 

 above it into the inter-articular cartilage in the Chameleon. 



