of the ventral cirrus; superior cirrus overreaching its lobe. Length 18". Nereis longissima, Johnston in Ann. Nat. Hist. v. 178. Heteronereis paradoxa, Oersted, Grænl. Annul. Dorsibr. 23. f. 50, 63, 64 & 66; Kroyer's Naturh. Tids. 1842, 116. Nereis paradoxa, Grube, Fam. Annel. 50. Hab. Coast of Ireland. Desc. The specimen before me is of the extraordinary length of 2 feet! but as it has become very soft in the spirits, it would perhaps not much exceed 18 inches when alive. It is of the thickness of a goose-quill, and of a pearl colour with olivaceous feet, which are very large and flexile. Head distinct, rather small, obtusely triangular; the antennæ minute and shorter than the palpi. No. XXXIII.-Heteronereis longissima. Proboscis 16 N.B. The numbers affixed to the Woodcut figures express the number of the segment from which the foot was taken that served for the figure; m means that the foot was from near the middle; and p, from near the posterior extremity of the body. Feet large, destitute of all horny prickles, but armed with powerful jaws, which are only faintly serrulated near the base. Post-occipital segment not larger than the second. Tentacular cirri short, not so long as the breadth of the segment. Segments very numerous. (No. XXXIII.) of the anterior pairs with three rather long papillary and equal branchial lobes, the dorsal cirrus not reaching much beyond their apices; but the posterior feet much resemble those of H. renalis. Although the size of an animal is not usually reckoned a good specific character, yet we know that every species has in this respect certain limits which it never either much exceeds or falls short of. For this reason, it seems to me impossible to regard Heteronereis longissima as a variety of H. renalis, notwithstanding the similarity in the structure and figure of the feet would induce that belief; and I have been fain to resort to the distinctions afforded by the jaws and proboscis for their separation. This is the only known species with a prickless proboscis; and the serratures of the jaws are likewise fainter than in any other I have examined. As the specimen of H. longissima is not in a good condition, some allowance will be made, should the outline given of the posterior foot be found not wholly exact; but I am confident that the general contour and proportions are accurately expressed. Before I examined this worm, I had mistaken it for a species of Phyllodoce, which it more resembles in size and general aspect than a Heteronereis, and it is obviously a transition species, proving the affinity of these two genera. The foliaceous lamellæ of the feet are quite similar in structure to the branchial leaflets of the Phyllodoce, and, from the manner in which they are veined, are evidently also branchial in their function. Obs. A large species, with much of the habit of a Phyllodoce. Post-occipital segment not longer than the second; tentacular cirri short, not so long as the breadth of the segment. Segments very numerous; the feet of the anterior with three rather long papillary and equal lobes, the dorsal cirrus not reaching much beyond the apex of the dorsal lobe. 4. H. margaritacea, jaws with five to six denticulations, plain at the apex; post-occipital segment twice as long as the second, with tentacular cirri about equal to its diameter; feet lobulated, the lobes oblique, the dorsal without a crest, and overtopped by its cirrus; foliaceous lamella one only, cordate; inferior cirrus with a papilla at its base. Length 4". Plate XV. fig. 3. Nereis margaritacea, Johnston in Ann. Nat. Hist. iii. 294. pl. 6. f. 3. Hab. The coralline region. Amongst the rocks at Milton, rare, Montagu. Coast of Berwickshire, rare. Desc. Body about 4 inches long, rounded dorsally, and flattened on the belly, of a uniform mother-of-pearl colour, iridescent, the feet tinted with a dusky pale green. Head corneous, brown, subquadrangular. Eyes four, very distinct. Antennæ and palpi similar to those of N. viridis, nor is there any material difference in the proboscis, but the jaws are armed with only five or six denticulations, and the point is longer and smooth. Tentacular cirri subequal, reaching to the posterior margin of the post-occipital segment, which is twice as broad as the following. Segments rather narrow; the anterior with small feet, but they become gradually larger as we reckon backwards, attaining their maximum of development below the middle, whence they again begin to get less. Superior cirrus longer than the branchial lobule; the inferior cirrus of the anterior feet simple, that of the more developed feet with a lobe and short filament at its base. Bristles in two considerable brushes, colourless, compound, the point long and setaceous. Spines darker. The species appears to be allied to the Nereilepas variabilis of Oersted, but they are distinct. PLATE XV. Fig. 3 a. The head of Heteronereis margaritacea, with the proboscis protruded. 3b. A jaw separated and magnified. 3c. The foot of the 12th ring. 3 d. A foot from near the middle of the body, viewed laterally. Fam. V. NEPHTHYACEÆ. NEPHTHYDEA, Grube, Fam. Annel. 52. Char. Body vermiform, tapered posteriorly, the anal segment with a single style: head small, angled, flattish, truncate in front, and furnished with four minute antennæ : mouth with a large clavate biarticulated proboscis, ciliated with two series of connivent papillæ at the longitudinally slit orifice, and with rows of similar sharp papillæ half-way down the posterior half: jaws two, small: no tentacular cirri: segments numerous, narrow, all of them footed: feet large, biramous, the branches wide apart, lobe-like, with a foliaceous lamina in front of each, and pendent underneath the superior a sickleshaped branchial process; the inferior with a short cirrus at its base: bristles from the foot-branches behind the lamellæ, in spread fascicles, slender, weak and setaceous, simple and compound, the latter spliced at its junction with the shaft, and with the terminal piece acicular: a spine to each fascicle. Margaritaceous: arenicolous. 14. NEPHTHYS. Nephthys, Cuv. Règn. Anim. 203. Lam. Anim. s. Vert. v. 313. Savign. Char. The only genus of its family. 1. N. cæca, dorsal lamella suboval, twice as large as its setigerous lobe; inferior lamella larger than the dorsal, broadly ovate or heartshaped, with a small cirrus at its base; bristles weak, rather loosely fasciculate, and not much protruded beyond the edge of the lamella; dorsal cirrus none. Length 6-10"; breadth 4". Nereis cæca, Fabric. Faun. Grænl. 304. Turt. Gmel. iv. 90. La Néréide aveugle a species of Aonis, Aud. & M.-Edw. Litt. de la Nephthys clava, Blainv. Dict. lvii. 483. Nephthys margaritacea, Johnston in Loud. Mag. Nat. Hist. viii. 341. f. 33. W. Thompson in Ann. & Mag. Nat. Hist. xiii. 439. Nephthys cæca, Oersted, Grænl. Annul. Dan. 41. f. 73, 74, 77-86; Kroyer's Naturh. Tids. 1842, 123. Grube, Fam. Annel. 53. Nephthys ciliata?, Rathke in Nov. Act. Acad. Cæs. Leop. xx. 171. Ray Soc. Rep. 1847, 507. Nereis (Nephthys) lineata, Dalyell, Pow. Creat. ii. 146. pl. 21. f. 4-10. Hab. The littoral region, common. Desc. Body from 6 to 10 inches long, tapered slightly towards the No. XXXIV.-Nephthys cæca. b a. Worm of the natural size. b. The proboscis extended, of the natural size. d. A foot viewed laterally, magnified. anterior, and more so towards the posterior extremity, flattish, ths of an inch in breadth, of a beautiful pearly lustre and colour all over, smooth, without spots or stains. The feet yellowish; ventral surface flat, perlaceous, with a purplish furrow down the centre. Head distinct, square, truncate in front, where there is a very short, apparently unjointed antenna on each outer angle, and a similar pair beneath. Mouth inferior, evolving a very large proboscis, sometimes of a pink colour, greyish in others, rough, with miliary granules, and its edge crested with numerous short papillary tentacula arranged in longitudinal series: it contains a cartilaginous tube formed of eight equal pieces, which is closed with two semicircular lips or valves continuous with the outer sheath, and fringed with a double series of longish tentacula; and, within this inner proboscis, there is a pair of small pointed horny brown jaws. Segments narrow, convex dorsally, the lines of separation indistinct in the centre, but strongly marked along the sides; about 140 in number (in two specimens of average size 143 were counted), the anterior streaked with pale lines across the base of the feet. Feet greatly developed, increasing gradually in size to about the middle of the body, whence they again decrease towards the tail, very deeply divided into two branches : the dorsal branch rather less than the ventral, furnished with a perpendicular lamellar somewhat ovate process, with a small appendage of the same character at its base, a small cirrus, and an elongate branchial filament curved like a reaping-hook; the setigerous processes obtuse, broad, shorter than the lamella; the inner armed with a row of long, and the outer with a row of short bristles: ventral branch much like the dorsal, the lamella larger, with a small cirrus at its base. Bristles dusky, longer than the processes, very slender, setaceous, smooth, simple, each brush with a brown spine. The short bristles look as if they were abruptly broken off, but they are uniform on all the feet, and appear to be pointed under the microscope. Anus terminal, superior; the segment small, apodous, terminated with a style. This worm is remarkable for the splendour of its colour, which is exactly similar to that of mother-of-pearl; but the silvery lustre is confined to a space down the back and belly, for the sides and feet are of a yellowish hue, the inner base of the feet reddish, and the bristles dusky. When the foot is removed, and placed under a magnifier, it has a sort of resemblance to a horse's hoof; and is a very wonderful and beautiful piece of mechanism. The creature lives in the sand, in which it burrows by means, principally, of its strong proboscis. With this, used as a wimble, it opens up the way, the body being held steady with the aid of the setigerous feet. It thus buries itself with almost incredible velocity: nor is it less active in the water, should it accidentally be removed from its furrow and cast in the open sea,-swimming rapidly, with a serpentine wriggling motion, and propelled, unquestionably, by the lamella which project from each side, like a double bank of oars. I From Nephthys Hombergii our species differs very much in the construction and form of the processes of the feet; while in the shape and colour of the body they seem very nearly to agree. To no other species which has been accurately defined can it be referred; but ours may be conjectured to be the Nereis clava of Leach. have no means of deciding the point; and Blainville has, it would appear, introduced such an almost inextricable confusion into the nomenclature of that species, that it might be scarcely advisable to restore the name. The figure he has given (Dict. pl. fig. 1) does not facilitate the solution of the question. To the marine Annelides in general, fresh water is a deadly poison (Loud. Mag. Nat. Hist. ii. p. 402*); and Dr. Drummond has told its effects on the Nephthys in an interesting manner:-"On putting one of them," he says, "into a basin containing some fresh water it sank to the bottom, and lay for a moment motionless, as if stunned. It then dashed here and there through the water, violently lashing its anterior and posterior ends from side to side; but this extreme *"Il est même à remarquer qu'il est peu d'êtres marins qui meurent aussi vite quand on les met dans de l'eau douce; il semble que ce soit pour eux une liqueur corrosive."--Blainv. Dict. des Sc. nat. Ivii. p. 409. |