lancelet

Any of various small chordate marine organisms of the subphylum Cephalochordata, having a long thin body with a notochord but no cranium or vertebrae, and usually found buried in sand.

A lance.

The sand-lance, amphioxns, or branchiostome, a skull-less fish-like vertebrate, representing a genus Branchiostoma or Ámphioxus, a family Branchiostomidæ or Á mphioxidæ, an order Pharyngobranchii, a class Leptocardii, and a ‘branch’ of vertebrates lately named Cephalochorda. See these names, and Acrania.

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.

any of a group of primitive marine animals, of subphylum Cephalochordata, having a notochord instead of a backbone

small translucent lancet-shaped burrowing marine animal; primitive forerunner of the vertebrates