184 CORE. FVow. TUE. 
lear crest. In Rhinolophus (Plate I. Fig. C) the trochlear crest 
is prominent and acute, and the intertrochlear groove is deep. 
The head of the radius does not extend internally to the exter- 
nal crest of the external condyle, which is here much like the 
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Figure 24.— Anterior limb of bat. 
flange of the Carnivora. The high development of this elbow- 
joint in the Chiroptera cannot of course be ascribed to impacts, 
but it may be ascribed to an equally effective cause, viz., the 
great mutual pressure of the parts, accompanied by torsion, 
when in action. The muscular tension during flight is very 
great, and inequalities already existing in the surfaces of the 
bones forming the articulation would tend, under the influence 
of torsions, to be exaggerated. The external and internal con- 
dyles of the humerus were already distinct in the ancestors of 
the bats, of which Galeopithecus may be regarded as the nearest 
living ally. The pressure of the tendon of the triceps extensor 
muscle, with its sesamoid bone, has tended to deepen the inter- 
trochlear groove. 
The elbow joint of the mole presents peculiarities of its own. 
The manus is incapable of supination in the usual way, but it 
reaches a position half-way between pronation and supination in 
the opposite direction ; that is, by the rotation of the distal end 
