number of joints exceeds 270, about forty of which at the posterior end are of a much paler colour, and appear to be a reproduction; the rest of the body is of a fine bronze, resplendent with changeable prismatic tints; the sides furnished with tridentate peduncles, from the middle of which issue a flat fasciculus of hair of a pale colour, and one large black bristle. About the 28th joint commence on each side branched cirri of a blood-red colour, which afterwards increase considerably in length; these originate from the upper part of each peduncle, and are usually hexafid, but unite above the base; they are not retractile, but are generally carried erect and spread, giving the animal a beautiful appearance. The upper lip is bilobate, behind which are five short tentacula, the middle one standing in the suture of the lip: between the two outer tentacula on each side is a small black eye. The first joint behind the head is broader than the rest, and destitute of peduncles. The posterior extremity is furnished with two small terminal cirri. The mouth is large and placed beneath, concealing most formidable jaws, or complicated fangs, which were protruded occasionally as the animal became sickly, and very frequently in the agonies of death when a few drops of spirits were added to the sea-water. This apparatus consists of three pairs of hooked fangs of a dark colour, one pair smooth, the others toothed, besides a pair of broad plates on the lower part of the mouth." "This is the largest species of Nereis yet discovered to inhabit the British shores, extending sometimes to 14 or 15 inches in length, and large in proportion. It inhabits rocky situations, and is found lurking under the broken fragments; but is rare *. "While the animal was in a glass of sea-water, the circulation of the colouring secretion, through the ramifications of the cirri, was a curious object, and appeared to be effected at the will of the animal; but when it became sickly, the circulation was slower, rising up through the branches of the cirri gradually, as in capillary tubes; and as soon as it expired, all the colour from these parts vanished." -Montagu. (a) Falmouth, W. C. Cocks, Esq. (b) South Devon, Mus. Leach. (c) Falmouth, W. C. Cocks, Esq. (d) Falmouth. (e) South Devon, G. Montagu. (f) Falmouth. 7. E. margaritacea. Eunice margaritacea, Williams in Ann. & Mag. Nat. Hist. ser. 2. xii. 408. pl. 14. f. 4. * Viviparous? See Ann. des Sc. nat. x. 159 (1848). 8. NORTHIA. Onuphis, Oersted, Grænl. Annul. Dorsibr. 19. Johnston in Ann. & Char. Body scolopendriform: head exposed, distinct, with two short thick antennæ, and five greatly elongated tentacula, two in front, and three across the occiput: eyes two, posterior: the first two segments dissimilar to the following, furnished with a superior and inferior cirrus, and with strong bristles, partly straight and partly hooked at the apex: the succeeding segments have three kinds of bristles, one stout, straight, and uncinate,-another slender, curved, and setaceous,-and another of small size, with a funnelshaped apex. Tubicolous. Obs. From the absence of pectinate branchiæ, which are present in Onuphis, I have placed the following species in a new genus, the character of which is borrowed principally from Oersted. 1. N. tubicola, the tube quill-like and horny, smooth and transparent posterior tentacula annulated at the base only. Nereis tubicola, Müll. Zool. Dan. Prod. no. 2625; Zool. Dan. i. 18. Leodice tubicola, Savign. Syst. Annel. 52. Nereidonta tubicola, Blainv. Dict. Sci. Nat. lvii. 477. Onuphis tubicola, Johnston in Ann. & Mag. Nat. Hist. xvi. 6. fig. Eunice tubicola, Fleming in Encyclop. Brit. edit. 7. 219. pl. 275. f. 14 & 17. Landsborough, Excurs. Arran, 49. Hab. The coralline region. Desc. Worm linear-elongate, somewhat compressed, but convex on both dorsal and ventral surfaces, which are smooth and polished; the colour a uniform yellowish-brown, finely iridescent. Head (No. XX. fig. 2) narrow, sinuated in front, with five much-elongated tentacula annulated at the base, the outer pair shorter than the three posterior by one-half. Eyes behind the base of the tentacula. Occipital segment without any appendage. Segments (fig. 3) narrow, the length about a third of the transverse diameter. Foot uniramous, with two fascicles of bristles, each fascicle with a spine (fig. 4), two forcipate spinets (fig. 5), and many lanceolate slender bristles (fig. 6), the upper half bent aside from the line of the shaft, setaceous, and sharp-edged. Superior cirrus setaceous, not projecting beyond the foot on the anterior segments, but becoming considerably longer on the posterior, annulated at the base. Inferior cirrus shorter, but setaceous. Anal segment with two styles. The worm lives in a tube which has a singularly exact resemblance to the barrel of a quill. It is about 4 inches long, and the upper portion is thinner than the lower, which is tough, and not easily cut with a knife. I made a vain attempt to form it into a pen. No. XX.-Northia tubicola. 5 3 1 6 1a. Cephalic segment with three long subulate tentacula. 1 & 2 a, b. Tentacular cirri. 2 c. The mouth, upper lip, formed of two large egg-shaped tubercles. 3. Section of anterior part of body, showing the cirrus above and below 4. A spine, one on each fascicle of the foot. 5. Forceps, two on each fascicle of the foot. 6. Lanceolate bristles, many on each foot, curved at the tip, and very sharp Let us see if, in its curious structure, we can find a key to the habits of the animal. We learn from Müller that it lives in soft mud, and one unceasing object of its life is the capture of prey. For this end, it must protrude the anterior portion of the body beyond its tube, and raise itself above the surface of the mud,-and remain, in this position, on watch. To enable the worm to do this with ease, is, I conjecture, the office of the forceps-like bristles of the feet with their ends, it may hook itself to the rim of the tube, and thus obtain a support without the waste of muscular power. A long watch is thus rendered less irksome, while at the same time the capacity to seize upon a passing prey is increased. The prey caught, analogy leads us to conclude that the worm will instantly retreat and sink within its tube, where it can feed without disturbance or fear. But as the entry and passage are narrow and unyielding, it seems to follow that the prey should be held by the mouth alone when in the act of being dragged within the tube, and hence surely the reason that the mouth has been furnished with the hard tubercles to the lips; for, when pulled together and put in contact, they must give a firmer gripe and hold than could otherwise be taken. The use of the tube is to protect the body from the pressure of the soft mud in which it stands immersed. When the tube is overset or cast out by the waves or accident, the worm leaves it, and becomes, in its turn, exposed to enemies. To protect itself from these while a new tube is being secreted, nature has amply furnished the Sao with a series of bristling lances on each side. These arms are of exquisite make, very fine and very sharp; and those of the upper bundle have their points bent and inclined towards those of the lower bundle, which are likewise bent to meet them. Arms like these will inflict wounds on the tiny assailants of the Sao sufficiently painful to repulse them; and a lethal wound is unnecessary. (a) Plymouth Sound, C. Prideaux. (b) Scotland, Lieut. Thomas, R.N.* 2. N. conchylega, the tube flattened, free, formed of agglutinated fragments of shells and gravel: posterior tentacula on a short basal joint. Onuphis conchylega, Sars, Beskr. 61. tab. 10. f. 28. Grube, Fam. Annel. 44. Sabella compressa, Mont. Test. Brit. 555. Turt. Brit. Faun. 203. Hab. The coralline region. Desc. Worm scolopendriform, a little narrowed towards each extremity, convex dorsally, more flattened on the ventral surface, and furrowed as usual in the median line; of a yellowish-brown colour, with faint iridescent lines across in the sutures. Head small, distinct, with two lobe-like palpi, and five greatly, but unequal, elongated tentacula. Eyes two, lateral, placed backwards. Segments numerous, narrow, subequal, with a protuberant foot on each side. The first and second pairs of feet project forwards, like buttresses, on each side of the head, and reach a little beyond its front margin. These feet (No. XXI. fig. a) are armed each with about four strong simple bristles (fig. b) curved slightly at the apex, which is strong and not very acute. The feet which follow protrude laterally, and are armed with an elongated dorsal and ventral cirrus, and with two small brushes of bristles. These bristles are all simple, smooth, slender, but unequal, the linear shaft bent obliquely so as to form a sort of falciform point (fig. 6). There is a spine (fig. d) in each brush, distinguished by its straight figure. There appear to be about fourteen rings thus furnished, when suddenly their character * Lieut. Thomas, R.N., has repeatedly seen the worm turn itself in its tube. To do this the head is reverted, and pushed down within the tube, between the wall and the body. The body is dragged in the same course, until the reversion is completed, and the head occupies the end that had been occupied by the tail. changes, for the remainder of the body is soft, with rather broader rings, full of a glairy mucus, and of egg-like bodies that communicate a mottled appearance to it. The feet of these rings are slightly protuberant, and the bristles, although all simple, are of four sorts:1st, the spines; 2ndly, some with a short curved sharp point (fig. c) ; 3rdly, others with a more elongated point (fig. 6); and 4thly, two with a strong shaft and a forcipate apex (fig. e). Between the two species of Northia there is a very exact resemblance in the form of the head and its various appendages, so that it would be difficult to obtain in them a character by which they might be distinguished. Northia conchylega has seven jaws, exclusive of the two pieces that constitute the under support; and the jaws are serrated with obtuse denticulations (fig.ƒ). The tube of Northia conchylega is fully 3 inches long andths broad, flattened like the scabbard of a sword, open at both ends, and constructed of fragments of old bivalve shells, of echini, and of gravel rudely agglutinated together, and encasing the proper case of the worm * : this is membranous, tough, and quite smooth. To fabricate the tube, the creature has the property of secreting a large quantity of a colourless glairy fluid, which is so tenacious that it may be drawn out into threads a foot in length without breaking. (a) Berwick Bay, Dr. Johnston. (b) South Devon, J. Cranch. It resembles the tube of Onuphis Eschrichtii of Oersted exactly (Grænl. Annul. Dorsibr. f. 45), but the two species are otherwise distinct. |