Note 51 — Chapter XX · BIRD-LIFE OF THE SPANISH SPRING-TIME.
Reading edition
The large irides and general appearance of this species seem to indicate crepuscular tendencies, and an affinity—obsolete or evolvent—to the Strigidæ, which is recognized in its generic name, Circäetus, next to the Harriers. But, in fact, the affinity is more apparent than real, for the Serpent-Eagle is of purely diurnal habits.