A. _Styelopsis grossularia_ on shell. B. Tadpoles of same, × 9. _a_, branchial; _b_, atrial orifice. (B, after Sir J. Dalyell.) ] The little Cynthiid _Styelopsis grossularia_ (Fig. 11), popularly known as the “Currant Squirter,” occurs in the form of bright red hemispherical blobs on stones and shells; when undisturbed, the branchial and atrial orifices expand and project upwards. The eggs are brilliant red in colour. Sir John Dalyell was the first to discover the tadpole form, which is about ⅒ inch long (Fig. 11, B), and to observe the tadpoles become fixed and develop into fixed Ascidians. He calls the active little swimming larvæ “Spinulæ,” from their resemblance to small pins. The family _Ascidiidæ_ includes forms with a gelatinous or cartilaginous test; the branchial and atrial orifices usually have 8 and 6 lobes respectively; the branchial sac is without folds. _Ascidia mentula_, described above, belongs to this family. _Chelyosoma_ is characterised by the test forming tortoise-like horny plates on the upper surface. The exhibited specimen of _C. macleayanum_ (Fig. 12) comes from Greenland; the upper hemispherical part of the test is divided into 8 plates; the branchial and atrial orifices are situated in the joints between the plates. [Illustration: Fig. 12. _Chelyosoma macleayanum_, slightly enlarged. _a_, branchial; _b_, atrial orifice. ] The fine specimen of _Phallusia mammillata_ from Naples consists of several individuals partly fused together; the branchial and atrial orifices are wide open, and the mantle can be seen through the thick knobby translucent test. In _Rhodosoma_ the test is modified so as to form stiff plates recalling the valves of a bivalve shell. One plate is attached to the rocks, the other closing against the first like a lid; the anterior end of the animal with its branchial and atrial orifices is visible only when the lid is open. The Mediterranean species _R. callense_ (Fig. 13) grows attached to the rocks. The little exhibited specimen is on a fragment of shell in front of a black patch. The figure shows specimens with the lid open and closed. [Illustration: Fig. 13. _Rhodosoma callense_, × 10. A, “valve” open; B, shut. _a_, branchial; _b_, atrial orifice. (After Lacaze Duthiers.) ] Family _Clavelinidæ_. The body is attached to a creeping stolon or mass of stolons, from which new individuals arise by budding. The other three families of Simple Ascidians included solitary forms, but the Clavelinidæ are social, and form colonies wherein each individual has its own test. _Clavelina lepadiformis_ (Fig. 14) forms graceful crystal vases about an inch in height. The figure shows one individual, but usually the processes at the base extend out as stolons whence other individuals arise.