. A catalogue of the British non-parasitical worms in the collection of the British Museum. Worms. attached to the head, and their insertion is always superior (fig. 1, o ; fig. 2, b). The palpi are more connected with the mouth, and their insertion is inferior (fig. 1, b b)*. The tentacula (fig. 1, c c) are filiform organs inserted, in pairs, on each side of the head, and of the post-cephalic segment, when this is apodous. 4. Mouth.—In the Annelides with a head obscurely defined, as, for example, in the Tubicoles, the mouth is usually terminal; but in all the cephalous genera it is on the ven
. A catalogue of the British non-parasitical worms in the collection of the British Museum. Worms. attached to the head, and their insertion is always superior (fig. 1, o ; fig. 2, b). The palpi are more connected with the mouth, and their insertion is inferior (fig. 1, b b)*. The tentacula (fig. 1, c c) are filiform organs inserted, in pairs, on each side of the head, and of the post-cephalic segment, when this is apodous. 4. Mouth.—In the Annelides with a head obscurely defined, as, for example, in the Tubicoles, the mouth is usually terminal; but in all the cephalous genera it is on the ventral or inferior aspect. It is either a simple mde aperture, or it is furnished with a proboscis (fig. 1 and fig. 2, e, e), which can be extruded at the will of the animal, although it is kept retracted and concealed in the state of quiescence. It may be considered as simply a portion or continua- tion of the alimentary canal. It is often armed with horny jaws however, that they do not contain any transparent parts, and are not furnished with any optical apparatus: they are simple swellings of the optic nerves, sur- rounded ^^^th a hlack pigment, sensible to light, and enable the worm to distin- guish between light and darkness,—between places which lie in shade and those which are exposed to the glare of day; but not imparting the power of recog- nizing the shape, or colour, or texture of bodies.—Ann. des Sc. Nat. torn. xxii. p. 25. See also in favour of their being eyes, Bourjot in Microsc. Journ. i. p. 77; and Cuvier in Analyse des Travaux de I'Acad. Roy. des Sc. 1828, p. 82, &c. ; De Quatrefages in Ann. des Sc. Nat. iv. (1845) p. 178. But M. de Quatre- fages has found in some species, especially in Torrea vitrea, eyes that have a crystalline lens, a choroid coat, a vitreous humour, a transparent cornea, &c. " Some Annelida have other eyes besides those on the head. M. Quatrefages believes that he has discovered them upon the branchiae of the Sabella;, and
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectworms, bookyear1865
