Lancelet n. : A small fishlike animal (Amphioxus lanceolatus), remarkable for the rudimentary condition of its organs. It is the type of the class Leptocardia. See Amphioxus, Leptocardia.

Example:
What is some info on the digestive, reproductive and circulatory systems of a Amphioxus (Lancelet)?

Taxonomy
vertebrates, Amphioxus, Lancelets, Lancelet, subphylum Cephalochordata, long way, sister group, free encyclopedia, chordate, genome, cephalochordates, Genus, kingdom Animalia, Epigonichthys, representatives, basal, Branchiostoma lanceolatum, centimetres.

Defination from the web:
... American Scientist Online - The Lancelet. Scripps Scientists Discover Fluorescence in Key Marine Creature. v • d • e ...