. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 387 and an inner layer of longitudinal fibres. The latter are connected with the former and also amongst themselves by net-like anastomoses. These dermal muscles cause the folds of the cuticle. Internally to the longitudinal muscles there is another layer of circular muscles. In the Chcetifera two hooked setre are present near the genital opening (fig. 311); these assist locomotion. There may also be present one or two circles of setre at the posterior end of the body (Echiurus). In the Chc
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. 387 and an inner layer of longitudinal fibres. The latter are connected with the former and also amongst themselves by net-like anastomoses. These dermal muscles cause the folds of the cuticle. Internally to the longitudinal muscles there is another layer of circular muscles. In the Chcetifera two hooked setre are present near the genital opening (fig. 311); these assist locomotion. There may also be present one or two circles of setre at the posterior end of the body (Echiurus). In the Chcetifera A. (fig. 311), the ante- rior part of the body is elongated to form a kind of proboscis, which projects im- movably and cor- responds to the prseoral lobe (prfe- stomium) of the Annelida. The mouth is placed ventrally at the base of the probos- cis. In the Achveta (Sipuncididce) this proboscis is want- ing ; the mouth is placed at the ex- tremity of the an- terior region of the body, which is sur- rounded with cili- ated tentacles and FIG. 312.—Sipuneulus nudm, laid open from the side (after IV. Keferstein). Ta, Tentacles ; O, cerebral ganglion ; VO, ven- Can be retracted by trai nerve cord; D, intestine; A, anus ; BD brown tubes means of retractor (ventral glands), muscles (fig. 312). Alimentary canal.—The mouth opens into a pharynx, which is sometimes furnished with teeth; this is followed by a ciliated intes- tinal canal, which is usually longer than the body and disposed in coils in the body cavity. The terminal portion of the intestine is. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. London, Swan Sonnenschein & co.
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