Page:Popular Science Monthly Volume 11.djvu/166

154 when the safety of person, or home, or young, is in danger. There is not much of the owlish face in our Surnia. The facial disk, so prominent an owlish trait, is by no means marked. Still, for all his looks and ways, this same Surnia is a true owl. To an unusual degree for his family, he is trim, compact, and graceful. Its favorite home is



in the arctic regions, where "it feeds chiefly on the field-mice (Arviculœ) which swarm in the sphagnous vegetation of those boreal lands; also upon small birds, grasshoppers, and other insects." In severe winters it comes southward, even to the Middle States.

The old philosophers said Nature abhorred a vacuum. Does it not appear from our owlish résumé that Nature has an aversion to the abrupt and disconnected? Is it not noticeable that, however natural any two great related groups of animal forms may be, they are not separated by sharp and wholly distinctive lines? There is a shading at the edges into each other. In Biblical speech, the progress of the Divine scheme is literally "little by little," and the lower group gives of the higher one, as Bishop Horseley in a different connection has said, "elegant adumbrations of sacred truth." Only when the extremes of the groups are set in contrast will the family differences best appear. Let one but look a barn-owl and a bald-eagle full in the face of each, and how clear their differentiation! But these are the typical representatives here brought face to face. Suppose we look a moment at Fig. 11, of the marsh-hawk, or harrier (Circus cyaneus, Linn.), and then recur to Fig. 10, of the day-owl, or Surnia. Now the differentiation almost fades away. How very like they are! But Surnia belongs to a more lowly tribe than does Circus. The marsh-hawk is an unmistakable falcon, and the other is assuredly an owl. But as respects this harrier, however clear as a whole the title to his