1) Amphioxus 2) Lancelet 
Cephalochordata (from Greek: κεφαλή kephalé, `head` and χορδή khordé, `chord`) is a chordate subphylum defined by the presence of a notochord that persists throughout life. It is represented in the modern oceans by the lancelets (also known as Amphioxus). Along with its sister phylum Urochordata, Cephalochordata can be classified ...
any member of the subphylum Cephalochordata of the phylum Chordata. Small, fishlike marine invertebrates, they probably are the closest living ... [4 related articles]
[n] - fishlike animals having a notochord rather than a true spinal column
noun fishlike animals having a notochord rather than a true spinal column
belonging or pertaining to the Cephalochordata.