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Show 464 ANNELIDES. self-impregnation. According to the observations of M. Montegre, the ova descend between the intestine and the external envelope to the circumference of the rectum, where they are hatched. The young ones issue, living, from the anus. M. Leon Dufour, on the contrary affirms that their ova resemble those of the Leech. The nervous 'cord is nothing more than a crowded suite of numerous little ganglia( 1 ). M. Savigny subdivides them again. His ENTERIONES have four pairs of small setre, eight in all, under each ring. Every one knows the Common Earth-worm-Lumbricuaterrestris, L.-with a reddish body, that attains nearly a foot in length, and which is composed of upwards of one hundred and twenty rings. The tubercle is near the anterior third. Under the sixteenth ring are two pores, the use of which is unknown. This animal traverses the soil in every direction, and swallows a quantity of earth. It also eats roots, ligneous fibres, animal fragments, &c. In the month of June it rises to the surface during the night, to seek for a companion in the process of copulation(2). His HYPOGJEONES have, besides, an azygous seta oh the back of each ring. The only species known is from America(3). Messrs Audouin and M. Edwards also distinguish the TRoPHONu:, which have four bundles of short setre on each ring, and on the an· terior extremity a great number of long and brilliant setre which surround the mouth( 4 ). (1) Conf. Montegre, Mem. du Mus., 1, p. 242, pl. xii, and Leon Dufour, Ann. des Sc. Nat, V, p.17, and XIV, p. 216, and pl. xii, B, f. l--4. See also the treatise of Morren, De Lumbrici Terrestria Historia Naturali nee nonJlnatomica, Bruss., 1829, 4to. (2) What is here stated is common to many species, first ascertained by M. Sa· vigny. He has distinguished twenty of them. See my Analyse des Travaux de 1' Acad. des Sc., 1821. M. Duges distinguishes six, but does not refer them ex· actly to those of M. Savigny. N.B. Muller and Fabricius speak of Lumbrici with two seta: to each ring, of which Savigny proposes to make his genus CLITELLIO, (Lumbricus minutus, Fab., Faun., Grrenl., f. 4), and of others with four and six seta:; but thei1· descriptions require to be confirmed and completed ere their species can be classed. (3) Hypogreon hirtum, Sav., Eg., Anne]., p. 104. (4) Trophonia barbata, Aud., and Edw., Littor., de la. France, Anne]., pl. x, f, 13-15. A.URANCHIATJE. 465 NAis, Lin. The Naides have an elongated body, the rings of which are less distinct than in the Lumbrici. They inhabit holes made by them in the ooze, froth which one half of their body projects and is constantly in motion. Black points are observed on the head of some of them, which may be taken for eyes. They are small worms, whose power of reproduction is as astonishing as that of the Hydrre. Several species are found in the rivers, &c. of France. Some of them have long setre( 1 ), And sometimes a long proboscis before(2), Or several small tentacula at the posterior extremity(3). Others have very short setre( 4). Certain Annelides, hitherto referred to the Lumbrici, which construct tubes of clay, &c., in which they live, might be approximated to this genus( 5). CLYMEN A, Sav. The Clymenre also appear to belong to this family. Their thick body has but few rings, which are mostly furnished with stout setre; a little higher, and near the back, is a bundle of finer ones. There are neither tentacula nor appendages to the head. Their posterior extremity is truncated and radiated. They inhabit tubes(6). (1) Nai'a elingui-8, Mull., Wurm., 11;-.N. litturalis, Id., Zool.. Dan., lxxx. (2) Nai'a proboscidea, Id., Wurm., I, 1-4, of which Lamarck makes his genus STILA.RIA. (3) Nai'l digitata, Gm., caxa, Mull., lb., V, the genus PRoTo, Oken. (4) Nai'a vermicularis, Gm., Ra:s., III, xciiV 1-7;-N. aerpentina, Id., :xcw, Mull., IV, 2-4;-Lumbricua turbife:r;, Gm., Bonnet., Vers d'eau douce, III, 9, 10, Mull., Zool. Dan., lxxxiv;-Lumbricus lineatus, Mull., Wurm., ill, 4-5. (5) Lumbricus tubicola, Mull., Zool. Dan., lxxv;-Lumb. sabellaris, lb., civ, 5. M. Lamarck unites them with the Nai's tubife:r;, and makes it his genus Tumnx; it requires, however, a new examination. (6) Clymena amphistoma, Sav., Eg., Annel., pl. i, f. ;-01. lumbricalis, Ott. Fabr., Aud. and Edw., Litt., de la France, Annel., pl. x, f. 1-6;-01. Ebiemi1, Aud., and Edw., lb., f. 8-12. VoL. Il.-3 I |