Mr. Street’s observations satisfied him that the period of incubation of this Owl is about three weeks. When they have young and are hard pressed for food, they hunt by day as well as by night, and at this time they hoot a good deal. The young are ready to leave their nest about six weeks after hatching. At this time their feathers are nearly all grown, except their head-feathers, which have hardly started. In the spring of 1872 Mr. Street found a young bird that had fallen from its nest. Though very small it was untamable, and not to be softened by any attentions. Its savage disposition seemed to increase with age. It readily devoured all kinds of animal food, and was especially fond of fish and snakes. It was remarkable for its cowardice, being always ridiculously fearful of the smallest dog, the near approach of one always causing extravagant manifestations of alarm. He was therefore led to conclude that it does not prey upon quadrupeds larger than a hare, that it rarely is able to seize small birds, and that reptiles and fish form no inconsiderable portion of its food. The young Owl in question assumed its full plumage in November, when less than eight months old. It was of full size in all respects except in the length of its claws, which were hardly half the usual size. Mr. T. H. Jackson, of West Chester, Penn., has met with fresh eggs of this Owl, February 13, 22, and 28, and has found young birds in their nests from the 2d of March to the 28th. Mr. Audubon states that while the Great Horned Owl usually nests in large hollows of decayed trees, he has twice found the eggs in the fissures of rocks. In all these cases, little preparation had been made previous to the laying of the eggs, the bed consisting of only a few grasses and feathers. Wilson, who found them breeding in the swamps of New Jersey, states that the nest was generally constructed in the fork of a tall tree, but sometimes in a smaller tree. They begin to build towards the close of winter, and, even in the Arctic regions, Sir John Richardson speaks of their hatching their eggs as early as March. The shape of the egg is very nearly exactly spherical, and its color is a dull white with a slightly yellowish tinge. An egg formerly in the old Peale’s Museum of Philadelphia, taken in New Jersey by Alexander Wilson the ornithologist, and bearing his autograph upon its shell, measures 2.31 inches in length by 2.00 in breadth. Another, obtained in the vicinity of Salem, Mass., measures 2.25 inches in length by 1.88 in breadth. In the latter instance the nest was constructed on a tall and inaccessible tree in a somewhat exposed locality. The female was shot on the nest, and, as she fell, she clutched one of the eggs in a convulsive grasp, and brought it in her claws to the ground. An egg obtained in Tamaulipas, Mexico, on the Rio Grande, by Dr. Berlandier, measures 2.18 inches in length by 1.81 in breadth.