. The animal kingdom, arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy. Zoology. 706 RADIATA. transparency of their textures ; and that the order Rotifera ought to constitute a separate class, and to have a place in the Articulated series. Rotifera. The animals of this class have usually an elongated form, and are perfectly symmetrical on the two sides. At the anterior extremity, we observe one or more rows of vibratile cilia; these are frequently arranged (as in the common Wheel Animalcule, Fig. 21, b), in a circular manner, and
. The animal kingdom, arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy. Zoology. 706 RADIATA. transparency of their textures ; and that the order Rotifera ought to constitute a separate class, and to have a place in the Articulated series. Rotifera. The animals of this class have usually an elongated form, and are perfectly symmetrical on the two sides. At the anterior extremity, we observe one or more rows of vibratile cilia; these are frequently arranged (as in the common Wheel Animalcule, Fig. 21, b), in a circular manner, and when they are in motion, an appearance of revolving wheels is produced, from which the class derives its appellation. In many species we find a prolongation of the body in front, extending beyond the ciliary apparatus; this, which sometimes bears one or more red spots that are supposed to be eyes, may be regarded as a head (Fig. 21, a). The body is covered with a double envelope, both layers of which are extremely thin and flexible in many species, whilst in others tbe outer one seems to possess a horny consistence, and may even contain siliceous matter. In the Stephanifcros Eichornii, this is so far detached from the body, as almost to form a sort of polype-cell, like that of the Bowerbankia ; and the cilia, instead of being disposed in circular rows, are mounted on arms like those of a polype ; so that the whole animal bears a strong resemblance to the Bryozoa, with which it forms the connecting link. _^ jl The body of the Rotifer vulgaris not being enclosed in any such dense envelope, is capable of considerable extension, and has much of the Vermiform aspect; this is increased when a slight contraction draws the external membrane into transverse wrinkles, that seem to indicate the segments of the trunk. The posterior extremity is prolonged into a tail, possessing three joints, which can be drawn up within each other. Within the external integument there are four longitudina
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectzoology, bookyear1854
