Volume I Part 37 (2/2)

Branches 4 to 7 serial; opening of cells in central rows, oval, sometimes square below; and the cell frequently produced into a shallow arcuate cavity. A short blunt spine on each side of the mouth. Marginal cells shallow, opening oval, margin much thickened, granulated: usually a short conical spine at the summit; a very minute sessile avicularium behind the outer edge, superiorly. Vibracula very large: setae serrated.

Habitat: off c.u.mberland Islands, 27 fathoms fine grey mud.

Colour white or yellowish; forms close rounded tufts 2 1/2 to 3 inches in height and width, composed of uniform dichotomously divided branches, about 1/8 of an inch wide, and which become wider towards their truncate extremities. The vibracula are very large, and though distinctly defined, are yet sufficiently transparent to allow a view of the lozenge-shaped cells. The central rows of cells vary in number from two to five, and the cells composing them are arranged with extreme regularity. The marginal rows are placed in a plane posterior to the central, and as above noticed, the cells of which they are composed are widely different from the central.

The only other species with which the present can be confounded is Caberea hookeri (Cellularia hookeri, Fleming) a British form. The latter species appears to differ from C. lata, chiefly in its having a large tubular spine on each side of the mouth of the lateral cells, and in each of the central cells, or nearly so, being furnished with an anterior avicularium, below the opening and to one side. The lateral sessile avicularium on the marginal cells is also much larger.

Fam. 5. Fl.u.s.tRADAE.

Polyzoarium expanded, continuous or encrusting. Cells disposed in straight series, which do not radiate from a centre.

17. Fl.u.s.tra, Linn.

a. Cells on one side only.

1. F. pyriformis ?, Lamouroux.

Cells pyriform, or barrel-shaped, prominent, marked with transverse wrinkles. Ovicells lofty, keeled in front, with a strong central, and two lateral longitudinal ribs.

Habitat: Ba.s.s Strait, 45 fathoms.

Sometimes small and parasitic, upon Sertularians and Polyzoa--sometimes independent, then of large growth, forming dichotomously divided fronds, with strap-shaped truncate, unequal divisions.

b. Cells on both sides. (Carbasea, Gray.)

2. F. denticulata, n. sp.

Cells much elongated, narrow; sides parallel, ends square; an upturned spine on each side at the oral end; sides of cell denticulate, denticles very numerous, small, acute. Avicularia irregularly distributed on the surface of the frond.

Habitat: Ba.s.s Strait, 45 fathoms.

Frond divided into numerous strap-shaped, truncated segments, of various widths; it attains a height of several inches. In habit it is very like some forms of F. truncata, and there is a Mediterranean species (undescribed ?) in which the cells are denticulate, much in the same way as in the present species, but otherwise quite distinct.

18. RETEPORA, Lamarck.

Character. (B.) Polyzoarium foliaceous, calcareous, or h.o.r.n.y, reticulate; cells only on one side.

1. R. cornea, n. sp.

R. ambigua ? Lamarck.

Cells oval, not very regularly arranged, in a continuous, foliaceous, subcircular frond; reticulated with oval s.p.a.ces, not as wide as the inters.p.a.ces. Ovicells large, galeriform, immersed, smooth.

Habitat. Off c.u.mberland Islands, 27 fathoms, fine grey mud.

This remarkable species is so completely a Retepore in construction, that it seems impossible to separate it from that genus, merely from the circ.u.mstance that its composition is more h.o.r.n.y than calcareous. The frond is more or less...o...b..cular, or rather is composed of more or less...o...b..cular or reniform folds, one over another, and attached as it were to a common centre. The substance is very thin and transparent, and the inters.p.a.ces are much broader than the elliptical s.p.a.ces.

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