THE LANCELET. 497 
THE last of the fishes is a creature so unfishlike that its real position in 
tue 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, 
its 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 
many of the insect tribe, and only marked bya 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 
bea 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 leptucephalus, 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, possessing well-developed 
eyes, gill-covers, jaws, and teeth ; whereas the Lancelet has no particular 
head, and neither eyes, gill-covers, jaws, nor teeth. 
