The lancelets, also known as amphioxi (singular, amphioxus), consist of about 30 species of . Other important contributions to amphioxus adult anatomy were given by Heinrich Rathke and John Goodsir. Kowalevsky also released the first.
Adult lancelets reach a length of about six to seven centimetres ( inches). There is little structural diversity within the group, the main difference between the .
Amphioxus, plural amphioxi, or amphioxuses, also called lancelet, any of certain members of the invertebrate subphylum Cephalochordata of the phylum.