helioscopic

“Reddish grey, sometimes almost olive green in colour, with white blotches and sparse, coarse bristles, the animal has no comeliness, and yet when a herd frolics in the water, rising in unison with graceful undulatory movements for air, and the sunlight flashes in helioscopic rays from wet backs, the spectacle is rare and fine.”

The Confessions of a Beachcomber