On June 15th, 1874, Mr. Wm. Couper, while collecting on Montreal Mountain, found a larva on Oak, which he kindly gave to me. It appeared fully grown, and was a little over two inches in length. Body onisciform ; general color, gray. Head heart-shaped, strongly bilobed, pale green, with white blotches, twelve short black hairs in front, and near the top of the head there are four small tubercles of a white color, each of which is tipped with a black hair ; head surrounded with a broken border of dark streaks.