AMPHIOXUS • E-FREE TRANSLATION.COM • Definition of Amphioxus

... the deductions of Haeckel founded upon them, concerning the larva of the ascidiae, a genus of marine mollusca of the order tunicata, and sees in a cord, to be found in this larva, most decided relationship to the spine of the lancelet fish or amphioxus, the lowest of all the vertebrates, it being yet doubtful whether it belongs at all to the vertebrates. 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. Out of ...

— The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality • Rudolf Schmid