ANATOMY.—Siebold’s “Anatomy of the Invertebrata” contains a good general account. Bertkau describes, in “Traschel’s Archiv für Naturgeschichte,” the mandibles in 1870, the respiratory-organs in 1872, and the sexual organs in 1875. Oeffinger describes the spinning-glands in “Archiv für Microscopische Anatomie,” 1860. EMBRYOLOGY.—Claparède, Utrecht, 1862, and Balbiani, in “Annales des Sciences Naturelles,” 1872, describe the growth of the egg from segmentation to hatching. H. Ludwig, in “Zeitschrift für Wissenschaftliche Zoölogie,” 1876, gives an account of the segmentation in eggs of Philodromus. HABITS.—Walckenaer’s “Histoire Naturelle des Apteres” goes over the whole subject. Blackwall, in “Researches in Zoölogy,” 1834, describes the web-making of Epeira, and the flying habits of spiders. Blackwall also writes on habits in “The Spiders of Great Britain and Ireland,” published by the Ray Society, 1864, and in various papers in “Transactions of the Linnæan Society,” 1833 to 1841. Menge’s Lebensweise der Arachniden in “Schriften der Naturforchenden Gesellschaft in Danzig,” 1843, goes over the whole subject, and is particularly useful on the sexual habits. The same author continues the subject in “Preussische Spinnen,” published by the same society, beginning in 1866, and not yet finished. The habits of the water-spider are described by Mr. Bell in “Journal of the Linnæan Society,” 1857. The trap-door spiders and their habits are described by J. T. Moggridge in “Harvesting Ants and Trap-door Spiders,” published by L. Reeve & Co., London, 1873, and Supplement, 1874. Prof. B. G. Wilder has published several papers on the habits of American spiders, the most useful of which are the following: on Nephila plumipes from South Carolina, “Proceedings of the Boston Society of Natural History,” 1865; Practical Use of Spider’s Silk in “The Galaxy,” July, 1869; Habits of Epeira riparia, Moulting of Nephila plumipes, and Nests of Epeira, Nephila, and Hyptiotes, in “Proceedings of American Association for Advancement of Science,” 1873; the Triangle Spider in “Popular Science Monthly,” 1875. INDEX. Abdomen, 12, 16. Adhesive threads, 67. Adult characters of spiders, 87. Agalena, web of, 55. Agalenidæ, 26. Age of spiders, 112. Air-sacs, 22. Air-tubes, 12. Anyphena, flying of, 84. Argiope, web of, 67. Argyrodes, 58. Attidæ, 28. Attus, flying of, 85. Bertkau, experiments on poison of spiders, 34. Blackwall, age of spiders, 112; experiments on poison, 35; on blowing out of threads, 80; on flying spiders, 82. Blind spiders, 113. Blowing of threads, 80. Breathing-organs, 16, 22.