Freshwater Polyzoa usually prefer dark places, but _Cristatella_ creeps along on the stones and pebbles in clear water, and in the sunlight. The polypides form three or more concentric rows on the upper surface. The statoblasts (Fig. 21, D) are circular, provided with a zone of air cells, and with hooked spines, the total diameter being about ¹⁄₃₀ of an inch. Sub-class II.—ENTOPROCTA. [Sidenote: Table Case A, upright part.] In this small group, both orifices of the alimentary canal open within the circle of tentacles, and there is no tentacular sheath. [Illustration: Fig. 24. _Pedicellina cernua._ × 27. [‘The Cambridge Natural History.’] ] The polypides are borne on contractile stalks. In the _Pedicellinidæ_ the stalks arise from a creeping stolon. In _Pedicellina cernua_(*) (Fig. 24) a stolon, creeping over seaweeds, etc., gives rise to stalked cups, the movements of which are vigorous: “the polypides, when excited, dash themselves vehemently from side to side. The heads are easily knocked off, but the decapitated stalks develop fresh ones. In _Ascopodaria_ the stalks are swollen at the base; _A. fruticosa_(*), from Port Phillip, Victoria, forms beautiful tree-like colonies. The _Loxosomidæ_ do not form colonies, owing to the buds becoming detached from the parent. The species of _Loxosoma_ are always found associated with some other animal, such as a worm or Tunicate. The tentacles of the polypide are arranged obliquely to the long axis of the body, hence the name of the family (_loxos_, oblique). _Loxosoma phascolosomatum_(*) occurs, in the form of delicate tufts, on the caudal end of the Sipunculid worm _Phascolosoma_. The individuals resemble pins with little white heads, and are capable of vigorous movements to and fro; occasionally a stalk coils itself up into a spiral. BRACHIOPODA. [Illustration: Fig. 1. British Brachiopods (_Terebratula_ and _Crania_). ] [Sidenote: Small Table Case A against the west wall to left of main entrance.]