CHAPTER XXIII. EXCRETORY ORGANS. Pp. 680-740.

Platyelminthes, pp. 680, 681. Mollusca, pp. 681, 682. Polyzoa, pp. 682, 683. Branchiopoda, p. 683. Chætopoda, pp. 683-686. Gephyrea, pp. 686, 687. Discophora, pp. 687, 688. Arthropoda, pp. 688, 689. Nematoda, p. 689. Excretory organs and generative ducts of the Craniata, pp. 689-737. General, pp. 689, 690. Elasmobranchii, pp. 690-699. Cyclostomata, pp. 700, 701. Teleostei, pp. 701-704. Ganoidei, pp. 704-707. Dipnoi, p. 707. Amphibia, pp. 707-713. Amniota, pp. 713-727. General conclusions and summary, pp. 728-737. Pronephros, pp. 728, 729. Mesonephros, pp. 729-732. Genital ducts, pp. 732-736. Metanephros, pp. 736, 737. _Comparison of the excretory organs of the Chordata and Invertebrata_, pp. 737, 738. Bibliography of Excretory organs, pp. 738-740.