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 A HISTORY OF SUSSEX Sertulariid^ 31. Sertularella polyzonias, Linnaeus. A little, straggling species with stem and branches of the same thickness throughout. The calycles are somewhat oval and arranged alternately on either side of the axis into which they appear to be sunk. The capsules are large and wrinkled. Often found growing upon annelid tubes, flustra, etc. Common in the trawl. Hastings. 32. Sertularella gayi, Lamouroux. This species resembles in type S. poly- zonias, but it is larger and of stouter build. The stem is compound with calycles alternate, short, stout and turned well out- ward, and having four slight denticles to the margin. The polypary is brown, the margins of the calycles appearing some- what lighter. Not uncommon in the trawl. Hastings. 33. Sertularella rugosa, Linnaeus. A small species often over-running flustra, and throwing up short branches with clusters of alternate wrinkled and oval calycles. The capsules resemble the caly- cles, but are much larger and contracted at the base. Common. Hastings. 34. Sertularella tenella, Alder. Hastings specimens appear to link together as nearly as possible Alder's species tenella and Hincks' species fuiiformh. The branches are about ^ inch in height, arising from the stem creeping over flustra. Caly- cles smooth, intermediate in slenderness, aperture with four denticles. The stem is bent at a right angle immediately above each calycle in a strongly zigzag manner. Capsules large, ringed and with four denticles. These points agree therefore with tenella, except in the calycles being smooth, not quite so slender, and in the capsules being toothed, in which respects the specimens resemble fusiformis. Hast- ings. 35. Diphasia rosacea, Linnaeus. A very delicate and graceful species, the laterally branched stems being flexible and plume-like. The calycles are tubular, bi- lateral, opposite, and bent straight outwards. The female capsule is thrown into vertical folds producing at the top a crown of spines of which two, one on either side, project, the others being curved over the centre. Habitat, upon other zoophyte stems, sponges, etc., from moderately deep water. Not uncommon. Hastings. 36. Diphasia attenuata, Hincks. A species very like rosacea and difficult to determine in the absence of the capsules, which are certainly the best specific guide. In this species the height of the stem joint above the offshoot of the calycles below is not so great as in rosacea, and the stem between each pair of calycles is not so attenuated. The calycles are also a trifle longer and narrower. The male capsule has a crown of spines directed horizontally outwards, and one central and vertical spine. Very common from the coralline zone, and from moderately deep water. Hastings. 37. ? Diphasia fallax, Johnston. The species is recorded with a query in the Natural History of Hastings before quoted. Although specimens are not at hand, the record appears well founded. Hastings. 38. Sertularia pumila, Linnaeus. This hydroid covers densely the bladder- wrack at low tide. The stem is only about ^ inch in height, and little branched. The calycles are tubular, short, bent out- wards and arranged in pairs, oppositely. Capsules ovate. Very common. Hastings. 39. Sertularia gracilis, Hassall. Of very similar growth to the last species but smaller, denser, and altogether more refined. Erect stems, not observed to branch. The calycle margin is thrown into two sharp points. Capsules ovate. This species over-runs other hydroidstems. Not very common. Hastings. 40. Sertularia operculata, Linnasus. This is a rich and luxuriant species and has been termed 'seahair.' It affects mussel shells and Laminarian stems. The stems are long, fine, wavy, branching and of equal thickness throughout. The colour might be almost called a dull golden. The calycles are arranged in pairs, oppositely, and the margins of the apertures are thrown into sharp points. Capsules balloon-shaped. Occasionally colonies of thiszoopiiyte might almost be said to rival in the number of its members the population of London. Very common from moderate to deep water. Hastings. 41. Sertularia ^licula, EWis znd Solander.* Hastings. 42. Sertularia abietina, Linnasus. The erect stems are about 6 inches in