Diagram of a lancelet. The mouth is surrounded by a circle of tentacles; below the notochord is a row of gill slits; the vent is near the posterior (right) end below.

Lancelet

Diagram of a lancelet. The mouth is surrounded by a circle of tentacles; below the notochord is a row…

The prehistoric vertebrate, the lancelet or Amphioxus.

Lancelet

The prehistoric vertebrate, the lancelet or Amphioxus.

"Section of <em>Ampioxus</em>, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural crest"&mdash;Finley, 1917

Section of a lancelet

"Section of Ampioxus, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural…

"Side view of <em>Amphioxus</em>: fs, fin supports; nc, notochord; ot, oral tentacles."&mdash;Finley, 1917

Side view of lancelet

"Side view of Amphioxus: fs, fin supports; nc, notochord; ot, oral tentacles."—Finley,…