Narrative of the Voyage of H.M.S. Rattlesnake, Commanded By the Late Captain Owe - Volume 1 by John MacGillivray (recommended reading txt) 📖

/>
Habitat: Bass Strait (?)

This species is placed doubtfully in the Rattlesnake Collection. It occurs, however, in Van Diemen's Land and New Zealand (Dr. Hooker) and is abundant in South Africa.

Fam. 4. CABEREADAE.

Polyzoarium entirely divided into ligulate dichotomous bi or multiserial branches; back nearly covered by large vibracula; avicularia sessile.

16. CABEREA, Lamouroux.

Selbia, Gray. op.c. Volume 2 page 292.

Cells bi-multiserial, in the latter case quincuncial. Posterior surface of branches concealed by large vibracula, which are placed obliquely in a double row, diverging in an upward direction from the middle line, where the vibracula of either row decussate with those of the other. Avicularia when present of the flexible kind, sessile on the front of the cell.

The remarkable feature of this genus resides in the vibracula, which here appear to attain their utmost development. Each vibraculum appears to belong not to a single cell as in Scrupocellaria, but to be common to, or applied to the backs of several. They are more or less pyriform or long oval in shape, and the two rows decussate with each other along the middle of the branch-giving in the narrower species, especially, much the aspect of an ear of barley, and in the wider of a straw plait. The walls of the vibracula are usually thin, and very transparent, so as to allow the outlines of the cells to be seen imperfectly through them. The upper and outer extremity of the vibraculum is bifid, and to the inner horn is articulated the seta, and from the notch between the two horns there is continued nearly, if not quite, to the inner extremity of the organ, and along its upper border, a shallow groove, in which is lodged the seta when in a state of rest. In most species the seta is serrated with distant teeth on one side.

Where there are more than two rows of cells, the marginal cells differ in conformation from the central.

As in Scrupocellaria, the opening of the cell is sometimes protected by a pedunculate operculum. The genus, therefore, may, like that, admit of being divided into sections, distinguished respectively by the presence or absence of a pedunculate operculum.

a. Operculatae.

1. C. rudis, n. sp.

Multiserial; opening of cells oval, margin much thickened, with a strong projecting upturned spine on each side in the central cells, and with three strong and long similar spines on the outer side, and a smaller one on the inner side in the marginal cells. Operculum spatulate, or pointed above, entire. Each cell of the central rows with two small avicularia in front, immediately below the mouth. Each marginal cell with a single large vibraculum in front below the mouth. Vibracula slender, very transparent. Setae short, not serrated.

Habitat: Bass Strait.

Colour dirty white: forms a broad frondose polyzoarium 1 1/2 to 2 inches, or perhaps more, in height. The branches, all disposed in the same plane, are flat, thick, and about 1/8th of an inch wide, composed of from four to six rows of comparatively small cells, which viewed behind appear lozenge or diamond-shaped, and arranged quincunically. It is not always easy to observe with accuracy the outline of the vibracula, owing to the extreme tenuity of their walls, but the groove along the upper border is very distinct and most usually has the seta lying in it. The avicularia on the marginal cells are very large, but not uniform in size. Along each border of the branches runs a bundle of radical tubes, the number of which diminishes as the branch ascends, each terminating in a vibraculum.

2. C. zelanica, Busk.

Selbia zelanica, Gray. Dieffenbach's New Zealand, volume 2 page 292.

Crisia boryi, Audouin. (Savigny Egypt plate 12 figure 4.)

Biserial; opening of cell oval or elliptical, rounded at each end, crossed in front, and thus divided into two nearly equal parts by a transverse calcareous band, from the lower edge of which depends a pedunculate, falciform operculum. Cells frequently produced upwards into a large arcuate ovicell. Vibracula ovoid, setae long, serrated.

Habitat: off Cumberland Islands, 27 fathoms, fine grey mud.

Slender: sufficiently distinguished by the peculiar form of the operculum. This part is so indistinctly represented in Savigny's figures, as to render it impossible to determine with certainty whether his species is the present one or not. The posterior view is much more like, but that is insufficient of itself to afford a specific character. The back of the branches exactly resembles an ear of barley. This species occurs in New Zealand, and also in South Africa.

b. Inoperculatae; opening of cell without an operculum.

3. C. lata, n. sp. ?

C. dichotoma ?, Lamouroux.

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 Cumberland 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. FLUSTRADAE.

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

17. Flustra, 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: Bass 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: Bass 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 horny, 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 spaces, not as wide as the interspaces. Ovicells large, galeriform, immersed, smooth.

Habitat. Off Cumberland 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 circumstance that its composition is more horny than calcareous. The frond is more or less orbicular, or rather is composed of more or less orbicular or reniform folds, one over another, and attached as it were to a common centre. The substance is very thin and transparent, and the interspaces are much broader than the elliptical spaces.

2. R. cellulosa.

Habitat: Bass Strait, 45 fathoms.

Not distinguishable from a Mediterranean specimen.

3. R. ctenostoma, n. sp.

Frond umbilicate, irregularly infundibuliform, spaces elongated, narrow, margins subdenticulate; interspaces as wide as the spaces. Mouth of cells tubular, projecting; with six or seven unequal acute expanding teeth.

Habitat: Bass 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 Bass 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 Flustra 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: Bass 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 bilabiata, n. sp. ?

C. labiata, Lamouroux.

Cells deeply immersed; mouths in some entire and unarmed; in others, with two acuminated 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: Bass 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. bilabiata are less rounded and