The more important new facts contained in the present paper are the following:
(1) Description of Acanthodrilus antarcticus, A. Rosæ, A. Dalei, nn. spp.
(2) The ciliation of the spermathecal appendix iu A. Rosæ.
(3) The presence in Eudrilus of two pairs of ovaries, connected by oviducts with a single aperture on each side; the oviducts are continuous with the ovaries.
(4) The description of Perichæta intermedia, n. sp., which differs from most species of Perichseta in having a single pair of nephridia in each segment, and in having a tubular atrium like that of Acanthodrilus.
(5) The presence of functional egg-sacs in the same species, in which the ova undergo their development surrounded by a follicular epithelium and with a mass of germinal cells attached to one pole, as in certain "Limicolæ," &c.
(6) The presence of a peripheral nerve plexus in Perichæta, specially developed in the neighbourhood of the setæ.
(7) The presence of a subintestinal blood-vessel in Acanthodrilus.
(8) The presence of a subneural blood-vessel in Perichæta.
(9) Description of the minute structure of the spermathecæ and the spermathecal appendices in Perichæta and Acanthodrilus; spermatozoa are only found in the appendices, the epithelium of which has largely undergone degeneration into a viscous substance, in which the spermatozoa are embedded.
(10) Description of some epidermic glands in Perichæta, which are possibly equivalent to the capsulogenous glands of Lumbricus.
(11) Description of certain organs in Perichæta and Acan-thodrilus which probably correspond to the "pericardial glands" of Lumbriculus. These consist of anetwork of capillaries with numerous spherical dilations crowded with cells; the whole network forms a compact series of organs clothed with chloragogen cells; they are found in the anterior segments only, and exhibit a more or less perfectly metameric arrangement.
(12) Description of a series of paired sacs attached to the septa of Acanthodrilus georgianus, which appear to be special glycogenic organs.