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Mr Appleton, The Influence of Function 



Certainly, eocene mammalia had femora of the same pattern; 

 and probably also musculature. The M. femorococcygeus (Fis?. 1 ) 

 may be first considered. In primitive types this muscle passes down 

 to be attached to the outer border of the femur below the third 

 trochanter (Fig. 2). From the latter the M. gluteus superficiahs 

 passes upwards and forwards. These muscles are often, and were 

 probably originally, continuous, as also with the M. biceps and 

 M. tenuissimus. Tupaia presents this general arrangement with 

 httle modification. 



A Cursorial hfe leads in all groups to a downward migration 

 of the attachment of the femorococcygeus, while this muscle tends 

 at the same time to gain a new upper attachment to the tuber ischii 



Fig. 1. Thigh musculature of hedgehog. A primitive condition. F.C. = femorococcy- 

 geus contmuous with superficial gluteus above. G.M. =gluteus medius. V.E "= 

 vastus extemus. (From a preparation by Dr W. L. H. Duckworth) 



of the pelvis. The femorococcygeus may even extend downwards 

 till it reaches the patella and then it gains a new function— knee 

 extension. The Fehdae show various degrees of specialisation. 

 Even within the single species Felis pardalis, the muscle may be 

 attached to either femur or patella (Parsons). The "long vastus" 

 of veterinary surgeons is none other than this transformed femoro- 

 coccygeus with (in Artiodactyla) accession of the superficial gluteus 

 which has also lost its femoral attachment. This muscle in the horse 

 plays an important part in bracing up the thigh during a stride 

 (Stillman). The superficial gluteus, if not thus incorporated in the 

 long vastus, undergoes, first, proximal migration, then regression 

 —as m Carmvora. Whether its persistence in Equidae is of some 



