The Lancelet also differs from the true vertebrates, in that it has no limbs.
The development of the Lancelet presents us with an instance of the two-layered larva, or Gastrula.
The lowest member of the vertebrate group, separated in fact from the true vertebrates and placed in a lower division all by itself, is the little animal called the Lancelet or Amphioxus.
In one respect, however, theLancelet reminds us of a fish: and that is in the arrangement of its muscles; these form a successive series of overlapping masses on each side of the body, as in a fish.
The lowest of the Vertebrata, the Lancelet (see p.
There is a huge gap between the Lanceletand the true vertebrates.
This much later appearance of the higher osseous fishes is quite in accordance with evolution, although some of the very lowest forms, the lancelet and the lampreys, together with the archaic ceratodus, have survived to our time.
We cannot suppose these to be nearly the earliest fishes, especially as the two lowest orders, now represented by the Amphioxus or lancelet and the lampreys, have not yet been found fossil.
In the lancelet there is no proper heart, the function of the heart being taken by a contractile blood-vessel situated on the ventral side of the alimentary canal.
The liver in the lancelet is a long diverticulum of the intestine.
There can be little doubt that the Tunicata form an offshoot from the primitive Chordate stock, and the structure of their larva in connection with that of the lancelet throws a large light on the nature of their common parents.
The simplest of all fish like vertebrates, the lancelet (Branchiostoma) has very small eggs, and in their early development it passes through stages that are typical for all many-celled animals.
But as the lancelet has no hard parts, no bones, nor teeth, nor scales, nor fins, no traces of its kind are found among the fossils.
The lancelet is a vertebrate reduced to its very lowest terms.
In the lancelet there is a single median organ supposed to be a nostril, a small depression at the front of the head, covered by ciliated membrane.
In the lancelet there is no trace of brain, the band-like spinal cord tapering toward either end.
Comparing a Cyclostome with a lanceletwe may see many evidences of specialization in structure.
The lancelet remains as a possible direct offshoot from it; the cyclostome with brain and skull is a possible derivative from archaic lancelets.
In development and structure this rod so resembles the notochord of the lancelet that it is regarded as a true notochord, though found in the anterior region only.
The sexually mature lancelet has, on the right and left of the gut, a series of metamerous sacs, which are filled with ova in the female and sperm in the male.
Hence we must once more thoroughly understand the palingenetic embryonic features of the lancelet before we go on to consider the cenogenetic forms of the craniota.
This one lowest vertebrate that merits the closest study--undoubtedly the most interesting of all the vertebrates after man--is the famous lancelet or amphioxus, to which we have already often referred.
Ascidia, affinity of the lancelet to; tad-pole like larvae of.
Goodsir perceived that the lancelet presented some affinities with the Ascidians, which are invertebrate, hermaphrodite, marine creatures permanently attached to a support.
These early ancestors of man, thus seen in the dim recesses of time, must have been as simply, or even still more simply organised than the lancelet or amphioxus.
Man is at the highest summit, the lancelet at the lowest root, of the vertebrate stem.
Especially in the lowest of all the vertebrates, the lancelet or Amphioxus, we have the oldest stem-forms completely preserved in the embryonic development.
Johannes Muller classed the lancelet with the fishes, although he pointed out that the differences between this simple vertebrate and the lowest fishes are much greater than between the fishes and the amphibia.
This straight, cylindrical rod (somewhat compressed for a time) is the axial rod or the chorda dorsalis; in the lancelet this is the only trace of a vertebral column.
The lancelet has a slender rod of cartilage along its back, and corresponds very closely with the ideal I have sketched of our primitive backboned ancestor.
Yet, as he illustrates its curious and unique structure, before we are aware, the lancelet is gone and a fish is in its place, and this fish with the potency to become a man in due time.
In the phylogeny of man, for example, what a vast hiatus yawns between the ascidian and the lancelet, and another between the lancelet and the lamprey!
Praie you sir stand vp, I am sure you are not Lancelet my boy Lan.
Tis now but foure of clock, we haue two houres To furnish vs; friend Lancelet what's the newes.
Praie you let's haue no more fooling about it, but giue mee your blessing: I am Lancelet your boy that was, your sonne that is, your childe that shall be Gob.
Ile tell my husband Lancelet what you say, heere he comes Loren.
I know not what I shall thinke of that: but I am Lancelet the Iewes man, and I am sure Margerie your wife is my mother Gob.
In the transition that once took place from one species of ascidian larva to a form similar to the lancelet fish, he sees the new branch diverging in the series of vertebrates.
In this, as in the case of the eye, the lancelet is lower than the ascidians, the insects, crustaceans, and many molluscs.
As the head end of the spinal cord of the lancelet developed, the cartilage enclosing it developed to protect it.
Into this the cerebral vesicle of the larval lancelet opens.
The human heart may present in degenerates all types from the pulsating vessel found in the lancelet up to that of the mammal.
In Xesurus the caudal lanceletis replaced by three or four bony tubercles which have no sharp edge.
From these investigations it has become clear that the individual development of the adherent simple Ascidian Phallusia agrees in most points with that of the lowest vertebrate animal, namely, the Lancelet (Amphioxus lanceolatus).
The Lancelet still lives widely distributed in different seas; for instance, in the Baltic, North Sea, and Mediterranean, where it generally lies buried in the sand on flat shores.
Mammalia The only one representative of the first class, the small lanceolate fish, or Lancelet (Amphioxus lanceolatus) (Plate XIII.
Lastly, one single member of the immense and diversified class of fishes, namely the lancelet or amphioxus, is so different from all other fishes, that Haeckel maintains that it ought to form a distinct class in the vertebrate kingdom.
These early predecessors of man, thus seen in the dim recesses of time, must have been as lowly organised as the lancelet or amphioxus, or even still more lowly organised.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "lancelet" in a variety of sentences. We hope that you will now be able to make sentences using this word.
