IV. A small gallery is devoted to Starfishes and their allies collectively constituting the class ECHINODERMA. Specimens of these are arranged systematically in table-cases 1–24; and in case 36 are specimens illustrating the anatomy of the skeleton, and models and figures showing the remarkable changes undergone by these animals in the course of their development. In a separate case on the east side of the gallery is a case containing specimens of a large Starfish to illustrate the variability in the number of rays from 4 to 7. In a case on the opposite side is shown _Luidia savignei_ from Mauritius, one of the largest of Starfishes. The Feather-stars (_Antedon_) are also members of this group; but the most beautiful and remarkable specimens in the gallery are the Sea-Lilies, or Crinoids, collected by the “Challenger” Expedition. One specimen was found attached to an old telegraph-wire taken up in the Caribbean Sea. These deep-sea Crinoids, of which representatives, now extinct, were abundant in earlier periods of the world’s history, are exhibited on tables in the corners of the gallery, by cases 37 and 38. Some of the larval stages of the Feather-stars (fig. 28) resemble stalked Crinoids. The wall-cases contain representatives of the groups collectively known as Worms. Case 1 contains the Tape-Worms or Cestoda, and the Flukes or Trematoda, the life-history of a species of each being illustrated by specimens, figures, and models. In case 2 the Round-Worms are illustrated by models of _Trichina_, and the anatomical structure of various other kinds is shown by the aid of diagrams. Case 3 contains specimens of free-living terrestrial and marine Worms, Leeches, and Gephyreans. Case 4 is devoted to specimens of Echinoderms preserved in spirit, especially Holothurians, such as Trepangs or Sea-Cucumbers, the Bêche-de-Mer of the French. [Sidenote: Shell Gallery.[15]] V. A large gallery is devoted to the great group of Shell-fish or MOLLUSCA, the exhibition of which is, however, mainly restricted to their shells. In some cases the form of the soft parts is, however, shown either by specimens in spirit or by means of models.