VESTIGIAL PARTS. 63 
part which has had important functions in an animal, 
and then has had its function gradually abrogated by 
another part, is more prone to be persistent in rudiment 
than remnants of organs of less importance. Darwin 
expresses this view of the matter thus: “Organs now 
of trifling importance have probably been of high im- 
Fic. 31.—A Horned Sheep with cervical auricles. 
portance to an early progenitor, and, after being slowly 
perfected at a former period, have been transmitted to 
existing species in nearly the same state, although now 
of slight use.” That mere disuse is insufficient to pro- 
duce abolition of a part is illustrated in a striking 
manner by the cervical auricles in goats, pig, and man. 
These ears or auricles, in so far as we know, subserve no 
