As these animals cannot be shown in a dried state, some of them, preserved in spirit, are placed in Wall-Case IV. According as they have or have not the sucking-feet of the Echinoderma, they are ordinarily divided into the _Pedata_ and the _Apoda_; the latter are represented by _Synapta_, which may attain to a great length, and by _Chiridota_; the Pedata are illustrated by the genera _Cucumaria_, _Psolus_, and _Holothuria_. Deep-sea investigations have revealed the existence of another group of specially modified Holothurians—the _Elasipoda_; these are remarkable for their well-marked bilateral symmetry and the distinctness between the dorsal and ventral portions of the body; the prominent processes on the dorsal surface are not contractile. An exhibition of some interest is to be found in a Table-Case against the wall, in which there are various specimens of the edible Holothurians—_trepang_ or _bêche-de-mer_; these were all bought in the market at Canton, and may be taken to be typical of the kinds offered for sale in various eastern countries. WORMS. By the name “Worms,” people commonly indicate a number of different forms whose relations with one another are by no means so close as those of a Holothurian and a Crinoid, or a Mussel and an Octopus. There are not, indeed, any common characters by the possession of which the worm-like animals can at once be distinguished from other animals. We take the divisions, examples of which are here represented, either by drawings, models, or specimens preserved in spirit separately. The groups referred to may be enumerated as follows:— _Platyhelmia._│Turbellaria. „ │Trematoda. „ │Cestoda. _Nemertinea._ │ _Nematoidea._ │ _Chætopoda._ │ PLATYHELMIA, or Flat-Worms.—These form the lowest and simplest division of the group.