Lancet

A small (6-7 cm.) fish-like animal that some consider to be the precursor of the vertebrates. Also known as amphioxus (from the Greek for "both (ends) pointed" or lancet worm. There are 22 known species of lancets belonging to two families:
          Phylum: Chordata
          Class: Cephalochordata (sometimes considered a subphylum)
          Family: Branchiostomidae (formerly Amphioxus) and Epigonichthyidae (formerly Asymmetronidae)

Lancets spend most of their time buried in sand where they feed on detritus. They resemble fish in many ways: a streamlined body, a notochord, separate sexes, and a dorsal fin that extends around the tail as a caudal fin and continues underneath the body as a ventral fin. However, they have neither bones nor cartilage and only the tiniest vestige of a brain. They are filter feeders, using cilia to drive water through the mouth and out the gill slits where food particles are trapped.

Lan"cet (?), n. [F. lancette, dim. of lance lance. See Lance.]

1.

A surgical instrument of various forms, commonly sharp-pointed and two-edged, used in venesection, and in opening abscesses, etc.

2. Metal.

An iron bar used for tapping a melting furnace.

Knight.

Lancet arch Arch., a pointed arch, of which the width, or span, is narrow compared with the height. -- Lancet architecture, a name given to a style of architecture, in which lancet arches are common; -- peculiar to England and 13th century. -- Lancet fish. Zool. (a) A large, voracious, deep-sea fish (Alepidosaurus ferox), having long, sharp, lancetlike teeth. (b) The doctor, or surgeon fish.

© Webster 1913.