The sticklebacks have been noted for their nest-building habits. The male performs this operation, and he is provided with a special gland for secretion of the necessary cement. Dr. Gill quotes from Dr. John A. Ryder an account of this process. The secretory gland is a "large vesicle filled with a clear secretion which coagulates into threads upon contact with water. It appears to open directly in front of the vent. As soon as it is ruptured, it loses its transparency, and whatever secretion escapes becomes whitish after being in contact with water for a short time. This has the same tough, elastic qualities as when spun by the animal itself, and is also composed of numerous fibers, as when a portion is taken that has been recently spun upon the nest. Thus provided, when the nuptial season has arrived the male stickleback prepares to build his nest, wherein his mate may deposit her eggs. How this nest is built, and the subsequent proceedings of the sticklebacks, have been told us in a graphic manner by Mr. John K. Lord, from observations on _Gasterosteus cataphractus_ on Vancouver Island, although the source of his secretion was misunderstood: "The site is generally amongst the stems of aquatic plants, where the water always flows but not too swiftly. He first begins by carrying small bits of green material which he nips off the stalks and tugs from out the bottom and sides of the bank; these he attaches by some glutinous material, that he clearly has the power of secreting, to the different stems destined as pillars for his building. During this operation he swims against the work already done, splashes about, and seems to test its durability and strength; rubs himself against the tiny kind of platform, scrapes the slimy mucus from his sides to mix with and act as mortar for his vegetable bricks. Then he thrusts his nose into the sand at the bottom, and, bringing a mouthful, scatters it over the foundation; this is repeated until enough has been thrown on to weight the slender fabric down and give it substance and stability. Then more twists, turns, and splashings to test the firm adherence of all the materials that are intended to constitute the foundation of the house that has yet to be erected on it. The nest, or nursery, when completed is a hollow, somewhat rounded, barrel-shaped structure worked together much in the same way as the platform fastened to the water-plants; the whole firmly glued together by the viscous secretion scraped from off the body. The inside is made as smooth as possible by a kind of plastering system; the little architect continually goes in, then, turning round and round, works the mucus from his body on to the inner sides of the nest, where it hardens like tough varnish. There are two apertures, smooth and symmetrical as the hole leading into a wren's nest, and not unlike it.