All the forms in this group inhabit fresh water, where, in the form of creeping or erect branching growths or masses, they grow attached to freshwater plants, tree-trunks, old wood, etc.; two species are capable of slow movement from place to place. The lophophore and tentacular crown of the polypide are horseshoe-shaped. The Order owes its name to the presence of a lobe guarding the mouth. In addition to the sexual, there is an asexual reproduction by means of peculiar internal buds termed statoblasts (Fig. 21). When the colony dies in the autumn, the liberated buds, securely protected in a horny capsule, retain their vitality till the spring; in due season the valves of the statoblast burst open, and the contents develope into a new colony. The statoblasts, which resemble small seeds, are usually provided with a ring of air cells, which act as a float, and in some species spines are present. [Illustration: Fig. 21. Statoblasts of Freshwater Polyzoa. A, _Fredericella sultena_ × 38; B, _Plumatella repens_ × 38; C, _Lophopus crystallinus_ × 28; D, _Cristatella mucedo_ × 28. [‘The Cambridge Natural History.’] ] [Illustration: Fig. 22. A, _Plumatella repens_, partly free, partly incrusting stem of water-weed. B, Cells magnified. (After Allman.) ] [Sidenote: Case A, upright part.] _Plumatella repens_(*) (Fig. 22) forms brown branching colonies, wholly or partly adherent to the surface of leaves of water plants, old wood, etc. The individual cells are club-shaped, and about a quarter of an inch long, each cell being attached to the upper back part of the cell below; the statoblasts (Fig 21, B) are simple oval bodies with a zone of air cells. _Plumatella_ (_Alcyonella_) _fungosa_ forms thick masses, composed of closely packed vertical tubes. A small specimen(*) surrounding a stick from Hampstead Ponds is exhibited. _Lophopus crystallinus_(*) occurs in the form of translucent gelatinous blobs, often attached to the slender stems of duck-weed. The statoblasts (Fig. 21, C) are elliptical and pointed at each end. The polypides are comparatively large, and can be easily observed through the transparent surface. When its delicate plumes are fully expanded, _Lophopus_ forms a beautiful object. _Cristatella mucedo_(*) (Fig. 23) occurs in the form of greenish translucent oval or worm-like colonies with the polypides on the convex upper surface. The animal slowly creeps about on its flattened under surface. [Illustration: Fig. 23. _Cristatella mucedo_, creeping over a stem of water-weed; × 6. (After Allman.) _a_, polypides with horseshoe-shaped crown of tentacles; _b_, statoblasts seen through the tissues; _c_, muscular sole by means of which the animal creeps; _d_, stem of water-weed. ]