in the open sea or crawling along the bottom, or they pass their life in burrows or definite tubes of various kinds." Amongst other peculiarities, some species are polymorphic. "Claparède was the first to show that Nereis dumerilii may occur in at least five different mature forms; these differ from one another in size, colour, mode of life, character of the eggs, &c." Fission and gemmation and the regeneration of lost parts are not the least uninteresting details of these in general beautifully-coloured worms, which vie in hue with butterflies, but whose tints are far more difficult to preserve.
Earthworms and Leeches have become so associated with the name of Mr. Beddard, and his 'Monograph of Oligochæta' is so widely known and generally consulted, that we might perhaps confine our remarks by saying that this portion of the volume is from his pen, and those of our readers who have recently read the "Earthworm Studies" which are appearing in our pages, will do well to consult this memoir also. The classification of Leeches is evidently attended with some difficulty. As no fewer than sixty-four colour varieties of the common Hirudo medicinalis are said to exist, "it is not wonderful that the labours of some systematists have been severe, and have provoked much criticism and alteration on the part of others." We are not therefore surprised at the remark of Sir J. Dalyell, which is quoted in a footnote: "It does not appear that the history of the Leech has advanced in proportion to the number of literati who have rendered it the subject of discussion."
Mr. Shipley has also written the account of "Gephyrea and Phoronis." The Gephyrea are exclusively marine, and have been the subject of considerable taxonomic discussion. They were formerly associated with the Echinodermata; Lamarck placed them near the Holothurians; and Cuvier "also assigned them a position amongst the Echinoderms." Quatrefages regarded these animals "as bridging the gulf between the Worms and the Echinoderms." The Sipunculids have a diet which seems to consist almost entirely of sand, and, as Mr. Shipley observes, "The enormous amount of sand and mud which passes through the bodies of the Sipunculids shows that they must take a considerable part in modifying the mineral substances which form the bottom of the sea. Just as Earthworms, as shown by
