THE HORSE IN MOTION. 45 



as of other muscles of the haunch, will be appreciated when we come 

 to the consideration of the fast paces. 



The external branch of the semi-tendinosus has by all anatomists 

 been' claimed as the posterior part of the vastus, while it was admit- 

 ted to be anatomically and functionally distinct. There is really no 

 relation between them except in their juxtaposition and in their super- 

 ficial appearance. Their connection is by a thin layer of cellular 

 tissue, while the connection between the branch in question and the 

 semi-tendinosus is most intimate, the partition being an aponeurosis 

 to which both are attached, as in penniform muscles, from which it 

 is impossible to separate the muscular fibres without laceration. I 

 have no doubt that the point will be conceded by all anatomists when 

 their attention is called to it, especially since it is shown that the 

 annexation I propose makes a complete organ of the semi-tendinosus, 

 with all its parts acting in perfect accord. 



The seini-membranosiis adjoins the last-described muscle and is 

 concealed by it in Plate V. Their relation is seen in the posterior 

 view, Plate IX., /. This muscle also has two origins like the last, 

 but that at the spine is by a thin tendon, and this branch is small 

 (Plate VI., a). The great mass of the muscle (/, Plate VII.) arises 

 from the lower surface of the ischium (Plate VII., c). It is thin pos- 

 teriorly where it overlaps the semi-tendinosus (at /, Plate IX.), but be- 

 comes thick where it unites with the so-called great adductor {g, Plate 

 VII.). The lower insertion is broad, the posterior portion of it is into 

 the fascia of the leg, and the anterior by tendon along with that of the 

 great adductor into the interior condyle of the femur opposite that 

 of the vastus ; its weight is six pounds. The thin posterior portion 

 of the muscle actins; on the fascia of tlie les: flexes it like the semi- 

 tendinosus, but the great mass of it acts in unison with the great 

 adductor (^, Plate VII.), with which it is so closely united that it is 

 difficult to separate them. 



The great addiiclor also rises from the ischium in front of the 

 last described, and is inserted into the internal condyle of the femur; 

 its weight is three and a half pounds, and its fibres are fifteen inches 

 in length, though fibres are thrown off along its course to the femur, 



