Polydinum, Say. Mass sessile, gelatinous, or cartilaginous ; poly morphous, composed of more or less multiplied systems, convex, radiated, each having a central cavity, and being more or less distinctly circumscribed. Individuals 10 to 150, placed at unequal distances form a common centre. P. aurantium, Milne-Edwards, has been found at Cullercoata.
A mouroucium, Milne-Edwards. Mass lobed or encrusting, sessile or pedunculated, fleshy or cartilaginous, composed of many systems, each having a central cavity. A. proliferum, M. Edwards, has been found in Belfast Bay. A. Nordmanni, M. Edwards, and A. Argus, M. Edwards, have been taken at Falmouth by Mr. Alder.
Leptoclinum, 31ffue-Edwards. Mass thin, sessile, encrusting, poly _ morphoua, coriaceous or gelatinous, composed of many systems ; vents opening into a common cloaca. The following species have been taken on various parts of the British coasts :—L. macadosum, L. asperum, L. aureum, L. gelatinosum, L. Listarianum, L. punctatum.
Distoma, Gaertner. Mass sessile, semicartilaginous, polymorphous, composed of many systems, usually circular. Anal and branchial orifices regularly and equally 6-rayed. Two species, D. rubrum and
D. variolosum, are British.
Botryll 118, Gaertner. The animals are grouped in single stars, and lie horizontally with the vent far from the branchial orifice. The branchial orifices simple and arranged around a common cloaca. B. Schlowri, Pallas. This is the species figured by Schlosser in the Philosophical Transactions.' It is one of the most beautiful, as it is one of the most common species of the family. Living specimens of this and the other species of Botryiliche are now in the Aquavivarium of the Zoological Society in the Regent's Park Gardens. The other British species are B. polycyclus, Savigny ; B. gemmeus, Say. ; B. vio laceus, Milne-Edwards; B. Smaragdus, M. Edwards; B. bivittalus, M. Edwards.
Botrylloides, Milne-Edwards. The stars formed by the systems of these animals are irregular and ramifying. The bodies are placed vertically and the two orifices approximate. The following species are British :—B. Say. ; B. aiticans, M. Edwards; B. rot ifera, M. Edwards ; B. rubrum, M. Edwards.
(Forbes and Hanley, history of British Mollusca.)