92 THE STRUCTURE OF MAN 
of the body. The elbow and knee joints are turned slightly 
outwards, the convexity of the former facing slightly backwards, 
that of the latter slightly forwards. The supporting portion of 
the limb looks in both cases outwards, and in each the anterior 
digit is rightly considered as the first of the series. 
Fia. 65.—LARVAL SALAMANDER. (After Hatschek.) 
A, with the limbs turned down; B, with the limbs turned up. 
In the higher Quadrupeds the anterior and posterior limbs 
undergo characteristic changes of position. First, the supporting 
segments of the two hmbs (ze. the manus and pes) are rotated 
inwards, so that their long axes, which were originally transverse 
to that of the body, come to be parallel with it [and their 
originally anterior borders become internal]; as a natural result of 
this, the first digit (pollex or hallux) becomes the innermost and 
the fifth the outermost. The rest of the limb, however, differs in 
its behaviour in the two members. In the fore-limb the humeral 
and radio-ulnar segments become flexed in such a way that the 
elbow is no longer directed outwards but backwards (cf. Fig. 65). 
In the hind-limb, on the contrary, the basal (femoral and 
tibio-fibular) segments are turned inwards, and so flexed that 
the knee is directed forwards. According to Hatschek the 
differences in position of the fore- and hind-lmbs involve only 
their basal segments, their terminal segments (manus and pes) 
being displaced identically. It would follow from this that the 
_changed position of the fore-limb has little if anything to do with 
the torsion of the humerus, which is very marked even in the 
Salamander, and must therefore be referred back to an early 
process antecedent to the changes under discussion. 
