Family _Doliolidæ_. The body is cask-shaped and surrounded by circular hoops. The branchial and atrial orifices are at the opposite ends. The branchial sac is pierced by two oblique bands of stigmata (Fig. 23 _sg_). The life history is very complicated. The egg develops into a tailed larva, which develops into a “nurse”; the latter is asexual, and produces three kinds of buds on a stolon, viz. (1) nutritive buds which provide the “nurse” with food, (2) foster forms which are set free as cask-shaped bodies with eight broad muscle-bands, and (3) sexual forms which are attached for a time to the foster forms, but which later become free and give rise to the egg. Order III.—LARVACEA. [Illustration: Fig. 24. _Oikopleura cophocerca_ in its “house” (after Fol); seen from right side, × 6. Arrows indicate course of the water; _x_, lateral reticulated parts of the “house.” ] The Larvacea are very minute Tunicata which live at the surface and swim by means of a tail-like appendage, resembling in this and certain other respects the tadpole larva of other Tunicata. They are able to form a temporary test or “house” many times larger than the body (Fig. 24). The organism itself, which is almost lost in its large test, is the little hammer-shaped body in the centre of the figure; the streaked areas bound a space in which the tail lashes vigorously. The animal can leave its test and secrete another in a few hours. The tail is attached to the under or ventral surface of the tiny little barrel-shaped body, and usually points forwards; a skeletal rod, the urochord, runs along its length. The branchial sac has two ciliated openings or gill-clefts leading directly to the exterior, and not opening like the stigmata of the other orders into an atrial cavity. The order contains one family, the _Appendiculariidæ_, and four genera, and is represented in all seas. _Oikopleura cophocerca_, one of the largest forms, is about half an inch in length. The exhibited specimens came from St. Andrews, Fife. Professor McIntosh reports that occasionally specimens of this species occur in immense quantities, the tow-nets being filled with them. THE STARFISH GALLERY. In the STARFISH GALLERY is exhibited a series of the animals belonging to the class _Echinoderma_; of these the Starfishes are the best known, while others are the Sea-Lilies, Sea-Urchins, and Sea-Cucumbers or Sea-Slugs. A small collection of various kinds of Worms is also exhibited in this Gallery (Wall-cases I.–III.). ECHINODERMA. Six table-cases contain the dried Echinoderms arranged in systematic order. The seventh is devoted to preparations, models, and figures illustrative of the structure and life history of various members of the group.