286 MOSTLY MAMMALS 
to relieve the animal of the inconvenience of pressure upon 
the neck.” 
Precisely the same description, inclusive of the sawing off 
of the top of the amalgamated horns, would apply to the 
two skulls of this breed in the British Museum. 
In the case of the many-horned breed of sheep it would 
seem that the redundancy in horn-development is more 
probably a disadvantage than a benefit to the animals in 
which it occurs. And if, as seems to be the case, the 
amalgamated horn in the unicorn-sheep tends to run into 
the neck of the owner so as to necessitate the amputation 
of the tip, the abnormality is altogether harmful; so that 
if it occurred in a state of nature it would probably soon 
disappear. 
This amalgamation of the horns in the unicorn-sheep 
presents a curious analogy to the so-called solid-hoofed pigs, 
which have been known from a very early period. “ From 
the time of Aristotle to the present time,” wrote Darwin, 
“ solid-hoofed swine have occasionally been observed in 
various parts of the world. Although this peculiarity is 
strongly inherited, it is hardly probable that all the animals 
with solid hoofs have descended from the same parents ; it is 
more probable that the same peculiarity has reappeared at 
various times and places.” The peculiarity is produced by 
the welding together of the middle pair of hoofs into a single 
large hoof. 
Although we may at present be unable to explain the 
curious variations displayed by different organs among 
animals under domestication, this is surely no reason why 
we should refuse to study them at all. 
