Narrative of the Voyage of H.M.S. Rattlesnake Volume I Part 33

Cells 9 to 13 in each internode; lateral branches given off between the first and second, or between the second and third cells above a joint. A small conical tooth, sometimes bifid, above and behind the mouth.

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

A small parasitic species, distinguished from C. denticulata, which it much resembles, by the less average number of cells in each internode, and the less number intervening between the origin of a branch and the joint below it, and by the small conical tooth or tubercle above and behind, or to the outer side of the mouth.

Suborder 2. CHEILOSTOMATA.

-- 1. Uniserialaria. Cells disposed in a simple series.

Fam. 1. CATENICELLIDAE. Cells connected by flexible joints.

5. CATENICELLA, M. Edwards (Lamarck An. s. Vert. tome 2 page 181.)

Cells arising one from the upper and back part of another by a short corneous tube, and disposed in a linear series, all facing the same way, and forming dichotomously divided branches of a phytoid polyzoary; cells geminate at the bifurcation of the branches; each cell furnished with two lateral processes usually supporting an avicularium. Ovicells either subglobose and terminal, or galeriform and placed below the mouth of a cell in front.

This interesting and important genus may be regarded as characteristic, not only of the present collection, but perhaps also of the Australian seas, as far as the Polyzoa are concerned. Thirteen species are here described, and as it has been found extremely difficult in most cases to identify any of them with the very few hitherto noticed forms, the synonyms given must be regarded as at least extremely doubtful.

Each cell arises from the upper and back part of another, with the intervention of a short corneous tube which is prolonged from the interior of one cell to that of the one above. The cell is furnished on each side at the top with a usually well-developed avicularium, in some species of huge size, and in some very minute, or entirely aborted. This avicularian process in most cases supports above a hollow process, which is sometimes closed and more or less elongated, const.i.tuting a conical or acerose spine, sometimes open above and a.s.suming the form of a shallow cup or receptacle. In some species both modifications of this portion of the lateral process are met with in the same specimen. This form of spine or cup--as the case may be, is always distinctly separated by a septum from the cavity of the avicularium itself. Below the avicularium there is also in many cases a third distinct cavity which is usually widely open, the opening being covered in very frequently by a convex transparent membrane, and its bottom apparently perforated by several minute foramina--from this part of the lateral process there is in many species a prominent ala or keel prolonged to the bottom of the cell--which ala not unfrequently divides into two branches, which, again coalescing at the bottom of the cell, circ.u.mscribe a more or less oval s.p.a.ce, the bottom of which is also perforated by minute foramina or apparent foramina, and which is often covered over by a transparent convex membrane. This membrane, however, as well as that which covers in the subavicularian s.p.a.ce, is more usually broken off and wanting.

The inferior oval s.p.a.ce above described is here termed the lateral area, and it is employed in the specific characters. It would thus be correct to say--that each cell is furnished with two lateral processes, each of which in the fully developed state consists of three distinct compartments--one superior, a cup or spine: a middle one, which is the avicularium: and an inferior; and it would appear that one or more of these elementary compartments of the lateral process may be more developed than the next, or sometimes entirely aborted. The mouth of the cell is situated at the upper part in front, and is of the same conformation as in the rest of the Cheilostomatous suborder. An important generic character consists in the gemination of the cell at each bifurcation.*

(*Footnote. Table 1 figures 1 and 2.)

These characters are common to all the species included in the genus, which furthermore admits of being subdivided into two extremely natural sections or subgenera (or perhaps into three). These subdivisions are named respectively the fenestratae, and the vittatae.

In the fenestrate division, in the whole of which the cells are of larger size and stronger than in the other, the wall of the cell appears to be const.i.tuted of at least two distinct laminae. The external lamina, on the front of the cell, is perforated by a certain number of holes, is wanting rather in a certain number of s.p.a.ces, for which s.p.a.ces the term fenestrae is employed. These apparent openings do not, therefore, penetrate into the cavity of the cell. But besides the fenestrae, there is, in some cases, a small central opening which does penetrate through the wall. In most cases the fenestrae are arranged in a crescentic, or rather horseshoe-shaped line, indicative, as it were, of the limits of a regular oval s.p.a.ce, in the front wall of the cell, the upper part of which oval would be formed by the mouth, and the remainder filled up by the deposition of calcareous matter, as happens for instance in the older cells towards the bottom of the polyzoary in certain Cellulariae, etc.

A further characteristic of the fenestrate Catenicellae is the terminal position of the ovicells. These organs are clearly transformed cells, or cells dilated to considerably more than their natural bulk, and a.s.suming a subglobose form. And what is worthy of remark, these terminal ovicells always have a sessile avicularium on the summit.

In the Vittatae the cell is smaller, and usually more delicate and transparent. They probably want the outer lamina, or have it very thin, and consequently present no fenestrate s.p.a.ces, and the front of the cell is beset (sometimes very sparingly) with more or less prominent, minute, ac.u.minate papillae. On each side, sometimes on the anterior aspect, sometimes quite laterally, is a narrow elongated band or vitta, as it is here designated, from which the distinctive sectional appellation is derived. This band or stripe varies in width and proportionate length and position in different species; it is slightly elevated, and marked with larger, or small circular discoid, or ac.u.minated eminences. This subdivision is further distinguished by the situation of the ovicells, which are not terminal, but occur at irregular intervals on cells in the course of the series. They are of the same galeate form as in many others of the Escharinae, but are not as in them placed above the mouth of the cell, but below it in front: and in all cases the shape of the ovicell-bearing cell is much altered from the rest, and in all the vittate species the cell upon which the ovicell is produced arises from its predecessor, not with the intervention of a short tube, but is immediately sessile upon it, by a broad base.

a. Fenestratae.

Cells large, fenestrate in front; ovicells terminal.

1. C. hastata, n. sp. ?

C. bicuspis ? Gray. Dieffenbach's New Zealand, Volume 2 page 293.

Fenestrae, 7 to 9, disposed in a crescent, and with elongated fissures radiating towards them from the median line. Avicularia supporting a large pyramidal pointed hollow process, compressed, and perforated before and behind by five or six small circular pores.

Habitat: Ba.s.s Strait, 45 fathoms, dead sh.e.l.ls.

Of a yellowish white colour, sometimes reddish. Forms fine bushy tufts, with long wavy branches, arising from a short common stem, and it attains a height of five or six inches. It appears sometimes to be parasitic upon other polyzoa, and is then much smaller. Its peculiar characteristics are the perforated and striated scutiform area on the front of the cell and the perforated, or apparently perforated pyramidal lateral processes above each avicularium; these processes are much developed, and give the cell the form of a broad inverted shear-head. It seems to be an abundant species in Ba.s.s Strait, and it occurs also in New Zealand. (Dr. Hooker's Collection.)

2. C. amphora, n. sp.

Cellaria catenulata ? var. B. Lamarck. Anim. sans Vert. Volume 2 page 180 2nd edition.

Cells oval, sides rendered straight upwards by the broad avicularia which are prolonged upwards into an acute spinous angle, and support a shallow cup. Front of cell with nine pyriform fenestrae, with fissures proceeding from their pointed ends towards an oval central perforation. An elevated band, extending from the sides of the mouth to the upper angular processes of the avicularia. An elevated flattened band along the middle of the back, which at the top sends off a narrower lateral band to each avicularian spine.

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

A fine species of a bright reddish brown, and in the younger cells very transparent. Forms small, irregularly branched bushes, four to six inches high and wide. It is peculiar by its extremely regular vase-like form of cell, which is given by the continuation upwards of the broad avicularia in nearly a straight line, and their prolongation into a sharp angular spine, on the inner side of which is a shallow cup-like cavity, whose sides are usually more h.o.r.n.y than calcareous. The number of fenestrae appears to be very constant.

The length of the branches before their dividing, and their straightness, together with the colour of this species, render it not improbable that it is the form intended by Lamarck (l.c.).

3. C. margaritacea, n. sp.

Cellaria vesiculosa ? Lamarck.

Cells oval or sub-globular, much compressed; avicularia short and broad, supporting a deep cup-like cavity. Fenestrae 5, large. Lower margin of mouth notched in the middle; back of cell minutely sulcated; sulci short, interrupted, and irregular. A small lateral area.

Habitat: Swan Island, Banks Strait.

A very beautiful species, the branches resembling strings of minute pearls. The pearly l.u.s.tre (in the dry state) owing without doubt to the minute sulci on the backs of the cells. These sulci are not, however, consequent upon the drying, because they are equally apparent and constant when the specimen has been immersed in fluid. The species may almost at once be distinguished by the notch in the lower margin of the mouth, which notch represents the central suboral opening present in some other species.

4. C. ventricosa, n. sp. Table 1 figure 1.

Cells oval, compressed, rather wide below; avicularia wide, supporting sometimes a cup-like cavity, sometimes a closed broad conical spine. The prehensile part of the avicularium itself small, seated in a deep notch below the ac.u.minate summit; lateral area large and well defined.

Fenestrae 7, with fissures radiating to a rounded central opening.

Anterior surface of cell studded with minute ac.u.minate papillae; posterior surface smooth, sometimes spotted.

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

Colour dirty white or brown. Habit stiff, stem strong, straight, branches short and crowded--probably attains a height of four or five inches. The only other species with which it can be confounded is C. amphora, from which it differs in the greater size and more irregular form of the lateral processes, in the presence of the minute papillae on the surface, and in the absence of the narrow longitudinal band on the back; instead of which the older cells in C. ventricosa exhibit a sort of broad scutum, almost covering the back of the cell and sending off two lateral bands on the sides of the cell, one pa.s.sing below the avicularium and above the lateral area, and the other towards the ac.u.minated apex of the avicularium. It also wants the raised bands which in C. amphora pa.s.s from the sides of the mouth to the apex of the avicularium in front. One large specimen presents a variety worthy of note--in this the backs of all the cells, except one here and there, exhibit (internally ?) numerous irregular-sized leopard-like spots.

5. C. plagiostoma, n. sp.

Cells short-ovoid; avicularia very large and long, ascending from near the bottom of the cell into an acute spinous point, and supporting a deep cupped cavity; mouth placed obliquely; front of cell divided into five large subtriangular fenestrae by four broad bands. Back of cell with a broad central band and two narrower bands branching from it on each side; surface of s.p.a.ces left uncovered by the bands on the back beset with scattered, long setose spines.

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

Colour brownish white; habit stiff, branches short. This species is at once recognisable by the peculiar oblique position of the mouth--the enormously developed avicularium usually only on one side of the cell, and by the sculpture of the cell--which appears as if it were swathed with broad tapes or bands. The wide s.p.a.ces left between the bands in front clearly represent the true nature of the fenestrae of other species. It is the only species furnished with elongated setose spines.

6. C. lorica, n. sp.

Cellaria catenulata ? Lamarck.

Cells elongated rhomboidal, truncated at each end. Fenestrae three, large, the lowest the largest, arranged in a triangle. Mouth very large; avicularia wide and strong; two lateral areae on each side, well developed; surface in front with a few indistinct circular spots around the fenestrae, and behind marked with faint longitudinal striae.

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

Colour white, transparent. A fine widely branching species, in which the catenulate aspect is more evident to the eye than in almost any other. It is at once recognisable by the rhomboidal scutate form of the cell viewed anteriorly, and, when the back is also viewed, the resemblance of the two aspects to the back, and breastplates of a coat of mail, is very striking. The structure of the lateral processes is more distinctly to be made out in this species than in any other. Each lateral process consists, first, of a deep cup-like cavity above; second, a middle compartment, the avicularium; and third, a third loculament below the avicularium, the wide opening of which is covered in by a convex transparent membrane. The bottom of this loculament appears to be perforated, and it is to be noticed also that there is a small central perforation in the septum separating it from the cavity of the avicularium. Towards the bottom of the cell, on each side, is a well developed lateral area of exactly the same conformation as the sub-avicularian loculament, and like it covered in by a convex transparent membrane. It might be supposed that these cavities were for the purpose of containing air, in order to render the otherwise heavy branches of the polyzoary buoyant. They, at all events, appear to be perfectly empty.

7. C. cribaria, n. sp.

Cells sub-globular, compressed, more or less alate. Avicularia large, without any superior appendage, and prolonged downwards into elevated lateral alae. Anterior surface with numerous small round fenestrae, placed at equal distances apart, and evenly distributed over the surface, the circ.u.mferential fenestrae being larger than the rest. A minute central perforation of a crescentic form, the lower lip projecting, and the upper lip, lingulate in the middle, falling behind the lower.