Volume I Part 38 (1/2)

2. R. cellulosa.

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

Not distinguishable from a Mediterranean specimen.

3. R. ctenostoma, n. sp.

Frond umbilicate, irregularly infundibuliform, s.p.a.ces elongated, narrow, margins subdenticulate; inters.p.a.ces as wide as the s.p.a.ces. Mouth of cells tubular, projecting; with six or seven unequal acute expanding teeth.

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

A very distinct and beautiful species. The frond is about half an inch wide, and though really umbilicate and subinfundibuliform, does not at first sight appear so, being much more expanded on one side of the centre than on the other.

19. ESCHARA, Ray.

1. E. lichenoides, M. Edwards. Mem. sur les Eschares. Ann. d. S. N. tome 6 page 31 plate 2 figure 3.

Habitat: Australian Sea, probably Ba.s.s Strait. (It also occurs in Algoa Bay.)

20. DIACHORIS, n. gen. Table 1 figures 10 to 12.

Cells separate, each connected with six others by short tubes; disposed in a horizontal plane, and forming a continuous irregular frond; free, or partially adnate.

The mode of arrangement and interconnection of the cells in this genus is remarkable, and highly interesting. It represents, in fact, a dissected Fl.u.s.tra or Membranipora. The cells are disposed in linear parallel series, and those of two contiguous series are alternate with respect to each other. Each cell is connected with one at either end in the same linear series by a rather wide short tubular prolongation, and with two on each side in the contiguous series by narrower tubes, so that each cell, except in the marginal rows, is connected with six others. It is this mode of interconnection of the cells that affords the diagnostic generic character. There is but one species in the present collection, but in Mr. Darwin's there are two others from the Straits of Magellan, as yet undescribed.

1. D. crotali, n. sp. Table 1 figures 10 to 12.

Cells erect, open in front, perforated on the sides and bottom; a lanceolate appendage articulated to each upper angle. Ovicell conical, placed on the upper edge.

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

The frond, though not strictly speaking adnate, as it seems to have no attachments, is usually spread loosely over other polyzoa. There is no appearance of a movable mandible in the lanceolate appendages, but which, nevertheless, most probably represent avicularia. These organs are of a lanceolate form, with an elevated ridge or keel along the back, and slightly concave beneath. They project in front, slightly depending; and at the base of each is a rounded eminence.

Fam. 6. CELLEPORIDAE.

Polyzoarium missive or crustaceous, composed of ovate cells in juxtaposition and arranged, more or less regularly, in linear series, radiating from a central point or line.

21. CELLEPORA, Otho Fabricius.

1. Cellepora bil.a.b.i.ata, n. sp. ?

C. l.a.b.i.ata, Lamouroux.

Cells deeply immersed; mouths in some entire and unarmed; in others, with two ac.u.minated conical lips; immediately beneath the apex of the posterior lip a small sessile avicularium. Ovicells subglobular, with a scutiform area on the upper surface, marked with several lines on each side, radiating from a central line.

Habitat: Ba.s.s Strait.

Parasitic on several zoophytes. This species to the naked eye exactly resembles C. pumicosa, but on closer examination several important differences will be observable. The cells in C. bil.a.b.i.ata are less rounded and less distinct than in C. pumicosa. As in that species, some of the cells are furnished with an avicularium, and others unprovided with that appendage; and again, some cells support an ovicell, whilst others do not. The mouth of the unarmed cells in both species is more or less circular and plain, but in C. bil.a.b.i.ata, even in the unarmed cells, the mouth is occasionally distinctly bil.a.b.i.ate. In C. pumicosa the avicularium is placed subapically on a solitary posterior obtuse mucro, but in C. bil.a.b.i.ata there are two such processes longer and more pointed, one in front and the other behind the mouth; the avicularium, as in the former case, being placed immediately below the apex of the posterior mucro. The ovicells also differ very much. In C. pumicosa this organ presents several rather large circular spots or perforations ? whilst in C. bil.a.b.i.ata it exhibits a scutiform or horseshoe-shaped area, marked with several transverse lines on each side of a middle longitudinal line.

Fam. 7. GEMELLARIADAE.