A still more beautiful species, with lengthened foot-stalks ringed at each end. The polype is remarkable for the protrusion and contractile power of its lips. It has about twenty knobbed tentacula. POLYZOA. Among Polyzoa the animal’s body is coated with a membraneous covering, like that of the Tunicated Mollusca, but which is a continuation of the edge of the cell, which doubles back upon the body in such a manner that when the animal protrudes from its cell it pushes out the flexible membrane just as one would turn inside out the finger of a glove. This oneness of cell and polype is a distinctive character of the group. Another is the higher organization of the internal parts. The mouth, surrounded by tentacles, leads by gullet and gizzard through a channel into a digesting stomach, from which the rejectable matter passes upwards through an intestinal canal till it is discharged near the mouth. The tentacles also differ much from those of true Polypes. Instead of being fleshy and contractile, they are rather stiff, resembling spun glass, set on the sides with vibrating cilia, which by their motion up one side and down the other of each tentacle, produce a current which impels their living food into the mouth. When these tentacles are withdrawn, they are gathered up in a bundle, like the stays of an umbrella. Our Plate I. contains the following examples of Polyzoa. VALKERIA CUSCUTA. _Pl._ I. _fig._ 3. From a group in one of Mr. Lloyd’s vases. Fig. 3 A is the natural size of the central group of cells, in a specimen coiled round a thread-like weed. Underneath this is the same portion enlarged. When magnified to this apparent size, the cells could be seen in different states, some closed, and others with their bodies protruded. When magnified to 3 D, we could pleasantly watch the gradual eversion of the membrane, then the points of the tentacles slowly appearing, and then, when fully protruded, suddenly expanding into a bell-shaped circle. This was their usual appearance, but sometimes they could be noticed bending inwards, as in fig. 3 C, as if to imprison some living atom of importance. Fig. B represents two tentacles, showing the direction in which the cilia vibrate. CRISIA DENTICULATA. _Pl._ I. _fig._ 4. I have only drawn the cells from a prepared specimen. The polypes are like those described above. GEMELLARIA LORICATA. _Pl._ I. _fig._ 5. Here the cells are placed in pairs, back to back. 5 A is a very small portion on the natural scale. CELLULARIA CILIATA. _Pl._ I. _fig._ 7