There are two pairs of nephridia, one posterior, the other anterior; and the members of the latter pair belong to different but successive somites. Testes and ovaries appear to be derived from peritoneal cells; the former are attached to the posterior aspect of a septum, the latter to the sides of the intestine in the second somite behind the testes. The vas deferens is composed of two ciliated funnels and ducts, which perforate a septum, unite, open into a glandular tube some distance from its end. A median and protrusible penis is continuous with the gland-tube. The oviducts are represented by two slits situated each on the apex of a papilla and leading into a short wide hibe. The genital products appear to be set free and to ripen in the coelome. There is a median azygos spermatheca in the testicular somite. The ova are laid singly in a delicate case, which is attached by a pedicle to the Astacus harbouring the worm.

Voigt, Arb. Zool. Zoot. Inst. Wurzburg, vii. 1885; viii. 1886. Dorner, Z. W. Z. xv. 1865. Lemoine, French Association for Advancement of Science, Reims, 1880. Development, Salensky, Archives de Biol. vi. Pt. i. 1885.

Naples, iii. 1883. Typhloscolex, Greeff, Z. W. Z. xxxii. 1879. Alciopidae and Tomo-pteridae, Id. Z. W. Z. xlii. 1885, with lit. quoted. Polyophthalmus, Meyer, A. M. A. xxi. 1882. Capitella capitata, Fischer, Marburg, 1884 (cf. Z. A. vi. 1884). Scoloplos armiger, Mau, Z. W. Z. xxxvi. 1882. Polydora ciliata and P. quadrilobata, Jacobi (Kieler dissert.), Weissenfels, 1883. Magelpna, Mcintosh, Z. W. Z. xxx. 1878 (cf. A. N. H. (4), xx. 1877). Terebellides, Steen, J. Z. xvi. 1882. Manayunkia, Leidy, Proc. Ac. Nat. Hist. Philadelphia, 1883.

Tube of Sabella, Mace, A. Z. Expt. x. 1882; of Onuphis, Schmiedeberg, Mitth. Zool. Stat. Naples, iii. 1883.

Gills of Serpula, etc, Orley, Mitth. Zool. Stat. Naples, v. 1884. Branchial skeleton of Sabella, Viallanes, A. Sc. N. (6), xx. 1886.

Muscular tissue, Rohde, Schneider's Zool. Beitrage, i. 1885.

Nervous system, Pruvot, A. Z. Expt. (2), iii. 1885; of Eunice Harassii, Jourdain, A. N. H. (5), xiii. 1884. Cf. Semper, Arb. Zool. Zoot. Inst. Wurzburg, iii. 1876-77, P.I43Organs of special sense. Tactile setae, Vejdovsky, System der Oligochaeten, 1885, p. 96; Langerhans, Z. W. Z. xxxiii. 1880, p. 271. Lateral line organs, etc, in Capitellidae, Eisig, Mitth. Zool. Stat. Naples, i. 1879; in Polyophthalmus, Meyer, op. cit. supra. Eyes, Carriere, Sehorgane der Thiere, Leipzig, 1885; cf. Graber, A. M. A. xvii. 1880; of Hyalinaecia, Pruvot, A. Z. Expt. (2), iii. p. 262. Otocysts in Arenicola, Jourdain, A. N. H. (5), xiii. 1884; in Aricia, Langerhans, Z. W. Z. xxxiv.

p. 88.

Digestive tract. Poison tooth of Syllidae, Langerhans, Nova Acta Cur. 42, 1881, p. 95. Glands of oesophagus, Graber, SB. Akad. Wien, lxvii. Abth. 1, 1873. Gizzard of Syllis, Haswell, Q. J. M. xxvi. 1886. Siphon of Capitellidae, Eisig, Z. A. 1, 1878; Fischer, op. cit. supra. Air-vesicles of Hesionidae and Syllidae, Eisig, Mitth. Zool. Stat. Naples, ii. 1881. Secretion of caeca in Aphrodite, Krukenberg, Untersuch. Physiol. Inst. Heidelberg, ii. 1882, p. 353.

Vascular system of Aphrodite, Selenka, Archiv. Nederland. f. Zool. ii. 1874-75; of Polynoe vasculosa, Claparede, Supplement (supra). Blood corpuscles, Bourne and Blomfield, Q. J. M. xxi. 1881. Blood of Arenicola, Krukenberg, Vergleich. Physiol. Studien, ii. 2, 1882, p. 87. Chlorocruorin, MacMunn, Chromatology, etc, Q. J. M. xxv. 1885.

Nephridia and sex organs, Cosmovici, A. Z. Expt. viii. 1879-80; of Capitellidae, Eisig, Mitth. Zool. Stat. Naples, i. 1879. Ovaries and ducts of Endrilus, Beddard, Z. A. ix. 1886.

Development, Salensky, Archives de Biol. iii. 1882; iv. 1883; of Serpula, Conn, Z. A. vii. 1884; Eupomatus, Hatschek, Arb. Zool. Inst. Wien, vi. 1885. Worm larvae, Fewkes, Bull. Mus. Harvard, xi., No. 9, 1883.

Viviparous Syllis, etc, Krohn, A.N. 35 (I), 1869. Egg-carrying Syllidae ( - Exo-goneae), Viguier, Animaux inferieurs de la baie d' Alger, A. Z. Expt. (2), ii. 1884.

Asexual reproduction: in Oligochaeta, Semper, Arb. Zool. Zoot. Inst. Wurzburg, iv. 1877-78; cf. op. cit. iii. 1876-77, p. 161, and Vejdovsky, Oligochaeten, p. 161; Lumbriculus, von Bulow, A. N. 49, 1882; in Syllidae, Langerhans, Z. W. Z. xxxii. l879, PP- 519-522; in Autolytus, Greeff, A. N. H. (4), i. 1868 (with lit.); in Syllis ramosa, Mcintosh, Challenger Reports, xii. 1885, p. 198; in Protula, Huxley, Edinburgh New Phil. Journal, i. (n. s.), 1855.

Metamorphosis of Nereis Dumerilii, Claparede, Supplement (supra); on Heteronereis, cf. also Ehlers, Borstenwiirmer, 1868, p. 451, &c; and Bobretzky, A. N. 37, (2), 1871, p. 385.

Pozvers of reparation: in Diopatra, Ehlers, Akad. programme, Erlangen, 1869; cf. A. N. 35 (2), p. 244; in Spio, Bobretzky, A. N. 37 (2), 1871, p. 385; cf. de Quatrefages, Hist. Nat. (supra), p. 124; in Oligochaeta, p. 208-9 ante- Phosphorescence, p. 201, and p. 208 with note 1.

Freshwater Polychaeta of Trinidad, von Kennel, Arb. Zool. Zoot. Inst. Wurz-burg, vi. 1883. Manayunkia, Leidy (supra). Boring Chaetopoda, Ray Lankester, A. N. H. (4), i. 1860; Mcintosh, ibid. ii. Pelagic forms, Viguier, C. R. 101, 1885; Greeff, Z. W. Z. xxxii. 1879.