_Resting bud_ An external bud provided with food-material in its cells, with a horny external coat and capable of lying dormant in unfavourable conditions. _Retractor muscles_ The muscles by the action of which the lophophore can be pulled back into the zooecium. _Statoblast_ An internal bud arising from the funiculus, containing food-material in its cells, covered with a horny coat and capable of lying dormant in unfavourable conditions. _Swim-ring_ A ring of polygonal air-spaces surrounding the statoblast. _Ventral surface_ (_Of zooecium_ or _polypide_) the surface nearest the anus; (_of statoblast_) the surface by which the statoblast is attached to the funiculus during development. _Zoarium_ The whole body of zooecia which are in organic connection. _Zooecium_ Those parts of the polyzoon-individual which constitute a case or "house" for the polypide. SYNOPSIS OF THE CLASSIFICATION OF THE POLYZOA. I. SYNOPSIS OF THE SUBCLASSES, ORDERS, AND SUBORDERS. Class POLYZOA. Small coelomate animals, each individual of which consists of a polyp-like organism or polypide enclosed in a "house" or zooecium composed partly of living tissues. The mouth is surrounded by a circle of ciliated tentacles that can be retracted within the zooecium; the alimentary canal, which is suspended in the zooecium, is Y-shaped and consists of three parts, the oesophagus, the stomach, and the intestine. Subclass ENTOPROCTA. The anus as well as the mouth is enclosed in the circle of tentacles and the zooecium is not very distinctly separated from the polypide. Some forms are solitary or form temporary colonies by budding. Most Entoprocta are marine, but a freshwater genus (_Urnatella_) occurs in N. America, while the Indian genus _Loxosomatoides_ (fig. 34, p. 176) is only known from brackish water. Subclass ECTOPROCTA. The anus is outside the circle of tentacles and the zooecium can always be distinguished from the polypide. All species form by budding permanent communities the individuals in which remain connected together by living tissue. Order I. GYMNOLÆMATA. Ectoproctous polyzoa the polypides of which have no epistome; the zooecia are in nearly all cases distinctly separated from one another by transverse perforated plates.