I. Protozoa, by Marcus Hartog. Porifera (sponges) by Igerna B.J. Sollas. Coelenterata & Ctenophora, by S.J. Hickson. Echinodermata, by E.W. MacBride. 1906.--II. Flatworms and Mesozoa, by F.W. Gamble. Nemertines, by Miss L. Shildon. Thread-worms and Sagitta, by A.E. Shipley. Rotifers, by Marcus Hartog. Polychaet worms, by W.B. Benham. Earthworms and leeches, by F.E. Beddard. Gephyrea and Phoronis, by A.E. Shipley. Polyzoa, by S.F. Harmer. 1901.--III. Molluscs, by the Rev. A.H. Cooke. Brachiopods (recent) by A.E. Shipley. Brachiopods (fossil) by F.R.C. Reed. 1895.--IV. Crustacea, by Geoffrey Smith and W.F.R. Weldon. Trilobites, by Henry Woods. Introduction to Arachnida and king-crabs, by A.E. Shipley. Eurypterida, by Henry Woods. Scorpions, spiders, mites, ticks, etc., by Cecil Warburton. Tardigrada (water-bears) by A.E. Shipley. Pentastomida, by A.E. Shipley. Pycnogonida, by D'Arcy W. Thompson. 1909. V. Paripatus, by Adam Sedgwick. Myriapods, by F.G. Sinclair. Insects, pt. I. Introduction, Aptera, Orthoptera, Neuroptera, and a portion of Hymenoptera (Sessiliventres and Parasitica) by David Sharp. 1895.--VI. Insects, pt. II. Hymenoptera continued (Tubilifera and Aculeata), Coleoptera, Strepsiptera, Lepidoptera, Diptera, Aphaniptera, Thysanoptera, Hemiptera, Anoplura. By David Sharp. 1901.--VII. Hemichordata, by S.F. Harmer. Ascidians and Amphioxus, by W.A. Herdman. Fishes (exclusive of the systematic account of Teleostei) by T.W. Bridge. Fishes (systematic account of Teleostei) by G.A. Boulenger. 1904.--VIII. Amphibia and reptiles, by Hans Gadow. 1901.--IX. Birds, by A.H. Evans. 1900.--X. Mammalia, by F.E. Beddard. 1902.