Fam. XVI. SABELLARIADÆ, HERMELLACEA, Grube, Fam. Annel. 83. HERMELLIENS HERMELLEA, Quatrefages in Ann. des Sc. nat. x. 12, 13 (1848). Char. Body vermiform, subcylindrical, of two distinct portions; the anterior segmented with setigerous and uncinated feet; the posterior narrow, without segments and apodous, like a caudal appendage: head disciform, armed with concentric circles of dissimilar and peculiar bristles, and cleft longitudinally into two equal halves, capable of being separated when the animal is protruded, and exposing the numerous tentacula which fringe the edges on their ventral surface mouth at the base of the cylindrical neck formed by the head-lobes, encircled with a somewhat extensile lip, emaxillary branchiæ in pairs on all the segments, dorsal, lingulate, or very narrowly triangular: feet in two series, the upper prominent, armed on some of the anterior segments with flat, but otherwise with hooked bristles, rudimentary or wanting on the second segment, and on the following segments furnished with small fascicles of capillary bristles. : 42. SABELLARIA. Sabellaria, Lam. Anim. s. Vert. v. 350. Grube, Fam. Annel. 84. Hermella, Savigny, Syst. Annel. 81. Quatrefages in Ann. des Sc. nat. x. 13 (1848). Char. Cephalic disk opercular, armed with peculiar and dissimilar bristles (pales) arranged in three or two circular series; post-occipital segment elongate, smooth, cleft beneath, and fringed with numerous tentacular filaments: thoracic portion with three pairs of lateral feet armed with lanceolate bristles in a flat brush: bristles of the abdominal segments setaceous: hooklets minute, peculiar, in a marginal series, and each attached to a long capillary filament. It is The Sabellaria are oviparous, and the ova are laid from spring to autumn. They live between tide-marks, and the alternate submersion and exposure to the atmosphere seems to be, according to M. de Quatrefages, very favourable to their growth and increase. not, however, a condition essential to their life. Specimens have been taken from shells, and from oyster-beds, dredged from the depth of several fathoms; and a very favourite locality is the root of the Laminariæ, which, on our northern shores, is rarely uncovered by the water. 1. S. anglica, opercular disk with three rows of dissimilar paleæ, the exterior palmate, with five to seven smooth digitations, the central not disproportionably elongate.-Tubes massive, irregular, formed of coarse sand, and cemented together by similar sand in the interspaces. Tubularia arenosa anglica, Ellis, Corall. 90. pl. 36. Sabella alveolata, Linn. Syst. xii. 1268. Williams in Ann. & Mag. Amphitrite ostrearia, Cuv. Règn. Anim. iii. 196. Sabellaria alveolata, Lam. Anim. s. Vert. v. 352; 2de édit. v. 605. Sabella alveolaria, Dalyell, Pow. Creat. ii. 175. pl. 25. f. 1-3. Obs. The tubes of this species form irregular masses, generally impacted amidst the branching roots of the large Laminariæ, or heaped on old shells and stones from the coralline region. The size of a mass cannot be ascertained, for it has no definite limits; and sometimes the tubes are single and separate*. They are formed of coarse sand and comminuted shells cemented together; but in general the mass is not so firm but that it is easily broken up by the fingers. As Ellis says, it is "of a dark sandy colour, brittle texture, rather light than heavy, porous on all sides, but on some distinguished by peculiar apertures." The tubes are irregularly mixed, usually somewhat flexuose, about an inch or an inch and a half in length; not in close apposition, and the spaces between are filled Iwith sand of the same kind as that of which the walls of the tubes are constructed. The aperture is circular and even, sensibly expanded, and often tinged with purple. "These tubes, as hath been observed above, are not of the same dimensions, nor always straight: but in this they all agree, that their bottoms are closed up, the animals filling up behind, as they advance forward, by a constant apposition of sandy particles, united together by a glutinous matter issuing from them.". -Ellis. Sir J. G. Dalyell has given the following interesting account of the species:- "This is a timid, lively, active creature, whose most prominent property is constructing itself an artificial dwelling of the grains of comminuted sand, intermingled with shelly fragments, or other indurated substances. But there seems a great difference in the solidity of the dwelling according to the position of the tube, or "Il ne faut cependant pas croire que la première forme toujours par la réunion de ses tubes des masses plus ou moins considérables; car nous avons trouvé souvent des individus solitaires dans les divisions radiciformes des fucus de nos côtes."-Blainville. perhaps the variety of the architects, which has never been the subject of sufficient observation. Thus we find the fabric, when a cylindrical segment running over some flattened surface, firm, durable, and capable of great resistance. It is not easily crushed. On the other hand, when cylindrical or alveolar, it appears to be always more brittle. Most of the dwellings of the Sabella are lined with a fine silky substance formed of an exudation escaping from the body, which, consisting of indurated glutinous matter, is very conspicuous on breaking up the alveolar mass of some old congeries. The animals testify a decided preference on choosing the materials of their habitations. While always preferring sand and comminuted shell, pounded glass is sparingly and reluctantly employed, and unless for a few fragments, it is soon entirely rejected. ་ "But there is a striking difference in the character of the tubes. One is short and confined, extending little beyond mere accommodation for the body; another is considerably prolonged, so as to afford a safe retreat in times of danger. The architect of a third seems to persist in advancing the fabric as long as it can procure materials. It never wearies of working*. Night is the chief season of architectural labour, though perfect idleness never leaves the day unoccupied. By means of the tentacular organs, and the cleft in the anterior part, grains of sand are selected and adapted to the precise spot, where glutinous matter secures them to the tube for sheltering its otherwise defenceless tenant." This tenant is wonderfully made. The body is less than an inch in length, of a subquadrangular form, slightly tapered from the thorax to the tail, which is terminated with a narrow caudal appendage, usually curved or bent upon the back: the anterior portion is generally coloured with purple; the abdominal is straw-yellow, becoming pink or fine red posteriorly. The head is in the form of a circular opercular disk divided into two equal halves by a slit, and consists of three concentric rows of bristles which have a pearl-like polish, and are very remarkable in their disposition and structure. In the centre of the disk we find the mouth in the form of an elliptical fissure surrounded with the inner row of bristles inclined towards the orifice. These bristles are triangulate, the portion imbedded in the parenchyma being elongate, narrow, and cylindrical, while the exposed portion is suddenly altered in direction so as to make a knee at the bend, whence it tapers gradually to a point. This portion is brown, and finely striated crosswise (No. XLIII. fig. 1). The middle circle consists of bristles which have a large bulged subtriangulate head, supported on a narrow stalk, entirely immersed in the flesh (fig. 2). The head is brown, hollow, beautifully striated crosswise, and ciliated on the edges of the opening in front. The bristles of the marginal circle look outwards, and form a denticulated fringe. Each bristle resembles a fork, with from five to seven unequal prongs (fig. 3). The shaft is narrow, elongated, with a sharp point, expanding above into a broad flattened hand, divided at the apex into sharp unequal * On the contrary, De Quatrefages could not get his specimens to work at all. -p. 27. points, the central ones more prolonged than those on either side. These rows of curious bristles are connected by a sort of membrane, No. XLIII.-Sabellaria anglica. 2 Bristles of operculum. 1. Exterior. 2. Intermediate. 3. Internal. 4. Diagram showing the relative position of the exterior and intermediate series. and firmly fixed by their long shafts in the flesh; and they are moveable, at the will of the animal, in different directions, and for different purposes, but which it is difficult to conjecture *. (a) Berwick Bay, Dr. Johnston. 2. S. crassissima, opercular disk with three rows of dissimilar paleæ, the exterior palmate, with five to seven digitations, the central not disproportionably elongate; branchiæ long and narrow. Tubes aggregate, erect, parallel, composed of coarse sand cemented into a mass. Sabella alveolata = Honeycomb No. XLIV. Sabellaria crassissima. Bristle of operculum. * This description does not agree with that of De Quatrefages. See loc. cit. p. 15. 605. Sabellaria crassissima, Lam. Anim. s. Vert. v. 352; 2de édit. v. Hab. Near low-water-mark on our southern and western coasts. 3. S. lumbricalis, opercular lid with three rows of dissimilar paleæ, the exterior palmate, with the central digitation greatly prolonged and spinous.-Tubes irregularly massive, formed of coarse sand. Sabellaria spinulosa?, Grube, Fam. Annel. 85. Sabella lumbricalis, Mont. Test. Brit. 549. Turt. Brit. Faun. 203. Hab. The coralline region, and oyster beds. Obs. The arenose masses formed by the tubes resemble exactly those of S. anglica, but the worm of S. lumbricalis is readily distinguished by the form of the exterior paleæ of the opercular crown. The body is 1" long, gradually tapered backwards, with a long caudal appendage, the abdominal portion red or purplish-red. The post-occipital segment is white and smooth, without lobes. The branchiæ are narrow, and as long as the diameter of the body. The abdomen has 24 segments, and becomes swollen, ovate-oblong, and roughish when it is about to terminate in the narrow tail. (a) South Devon, George Montagu. (b) Berwick Bay, Dr. Johnston. Fam. XVII. SERPULIDÆ. SERPULACEA, Grube, Fam. Annel. 85. Char. Body vermiform, roundish, with short segments, usually divided into the thoracic and abdominal by the relative position of the bristles and uncini: head amalgamated with the following segment, not noticeable in the full-grown animal: the first segment generally encircled with a collar, and furnished with a tuft of bristles on each side mouth anterior, placed between the branchiæ, edentulous: feet almost always biserial; in the thoracic division the dorsal are setigerous tubercles, the ventral transverse linear series of uncini; in the abdominal and longer division the lineated uncini are dorsal, and the setigerous tubercles ventral; and sometimes these are wanting, as are seldomer the uncinated series: bristles simple, usually lance-shaped and sharp: uncini siphonate: branchiæ attached to the vertex, flabellate, in two divisions, the rays usually pectinated, and radiating from a common cartilaginous base. Tubicolous. |