. The popular natural history . Zoology. THE LANCELET. 497 The last of the fishes is a creature so unfishhke that its real position in the scale of nature was lung undecided, and the strange little being has been banded about between the vertebrate and invertebrate classes. Between these two great armies the Lancelet evidently occupies the neutral ground, iis structure partaking with such apparent equality of the characteristics of each class, that it could not be finally referred to its proper rank until it had been submitted to the most careful dissections. In fact, it holds just such a posi
. The popular natural history . Zoology. THE LANCELET. 497 The last of the fishes is a creature so unfishhke that its real position in the scale of nature was lung undecided, and the strange little being has been banded about between the vertebrate and invertebrate classes. Between these two great armies the Lancelet evidently occupies the neutral ground, iis structure partaking with such apparent equality of the characteristics of each class, that it could not be finally referred to its proper rank until it had been submitted to the most careful dissections. In fact, it holds just such a position between the vertebrates as does the lepidosiren between the reptiles and the fishes. It has no definite brain, at all events it is scarcely better defined than in. LANCELET.—[Amphioxtis lanceolattcs.) many of the insect tribe, and only marked by a r ther increased and blunted end of the spinal cord. It has no true heart, the place of that organ being taken by pulsating vessels, and the blood being quite pale. It has no bones, the muscles being merely attached to soft cartilage, and even the spinal cord is not protected by a bony or even horny covering. The body is very trans- parent, and is covered by a soft delicate skin without any scales. There are no eyes, and no apparent ears, and the mouth is a mere longitudinal fissure under that part of the body which we are compelled, for want of a better term, to call the head, and its orifice is crossed by numerous cirrhi, averaging from twelve to fifteen on each side. Altogether, it really seems to be a less perfect and less developed animal than many of the higher molluscs. The general aspect of the Lancelet is not unlike that of another fish called the leptocephalus, the delicate transparent body and the diagonal arrange- ment of the muscles causing a considerable resemblance between the two. But the leptocephalus is at once distinguished by its head, which, although very small in proportion to the body, is yet perfect, pos
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
