_Diazona violacea_, from Cornwall, forms beautiful purple disk-shaped colonies in which the ascidiozooids arise from a basal mass of stolons. Sometimes the ascidiozooids die down, leaving only a smooth violet pad, which in due time produces a new crop of ascidiozooids. [Illustration: Fig. 14. _Clavelina lepadiformis_; diagrammatic, showing the anatomy. The oval bodies are the eggs; at lower end lies the tubular heart; the root-like processes at the base grow into stolons, whence other ascidiozooids arise. ] [Illustration: Fig. 15. _Perophora listeri_; A, slightly, B, further magnified. Ascidiozooids in right, left, and lateral aspects. _a_, branchial; _b_, atrial orifice. ] The remarkable _Rhopalæa neapolitana_, from Naples, may be roughly compared to an hour-glass with a very long constriction. The test is smooth in the upper part, but knobby and encrusted with foreign bodies below. The upper or thoracic end contains the branchial sac, and the lower or abdominal portion the stomach, heart, and reproductive organs, the gullet and intestine traversing the whole length of the narrow central region. Although from its general structure _Rhopalæa_ is a Clavelinid, it is not certainly known to produce buds. _Perophora listeri_ (Fig. 15) occurs in the form of little jelly-like transparent blobs rising by short stalks from a silvery thread-like stolon. Owing to their small size and transparency, it is possible to examine specimens alive under the microscope, the currents passing through the stigmata in the walls of the branchial sac, and the beating of the heart being distinctly visible. The rapid motion of the cilia surrounding stigmata gives the appearance of dark wheels all rotating in the same direction. The heart beats so as to drive the blood current so many times in one direction, and then after a short pause, in the reverse direction. The exhibited specimen growing on an oyster shell, is from Plymouth. _Sub-order 2._—ASCIDIÆ COMPOSITÆ. The Compound Ascidians are fixed forms, which give rise to colonies by budding, the individuals being immersed in a common mass and not possessing separate tests.