When we are dealing with the criminality of animals, concerning which a large body of evidence has now accumulated, it is necessary to discriminate. It is well recognised by veterinary surgeons that certain horses are inclined to be undisciplined and revengeful, and that these characteristics are associated with distinct cranial anomalies; the Arabs believe these qualities to be hereditary. There is here certainly a very close analogy to the instinctive criminal; but we are dealing with an animal greatly modified by man, and these vices are not recorded as exercised against their own species so much as against man. The case (apparently well authenticated) of the horse who pretended to be lame, to avoid going on military exercise, can scarcely be called criminal; from a horse's point of view this might be regarded as a justifiable ruse. The same may be said of the action of the dog who, finding his favourite place occupied by another dog, went outside and set up such a furious barking that the usurper came out to see what was the matter, when the rightful owner immediately pounced on his old corner. Such a ruse, even though perpetrated against one of the same species, is not anti-social. It is only when we are dealing with animals of the very highest order of intelligence that we find any manifestations that can be at all fairly described as criminal. Thus among the highly intelligent castors, the lazy castor is pitilessly chased away by his fellows, to die of hunger, alone, far from the colony. Idleness, as we know, is a very fundamental characteristic of the criminal, and the strongly marked social reaction that we see here shows that the castors have recognised this. Something of the same kind is seen among elephants. Certain elephants, called rogues, lead a solitary and unnatural life, and are lacking in the humane and gentle disposition peculiar to elephants generally. The anti-social character of these elephants is recognised by their fellows, and when the solitary elephant endeavours to penetrate into the family life of the ordinary elephant he is everywhere repulsed, and naturally grows still fiercer and more anti-social. Such examples as these are the nearest approaches among animals to what we call criminality.