In the two other subphyla of the chordates, Cephalochordata and Urochordata, the notochord is either maintained in the adult (Cephalochordata such as Lancelets) or present in the larval form and lost during metamorphosis into the adult form (Urochordata such as Tunicates).    From Wordnik.com.  [Haeckel had a point - The Panda's Thumb] Reference

Tunicates (Urochordata) do not have a closed circulatory system, only craniates have the first epithelial ducts that transport oxygen to the locomotion and digestive system-related muscles.    From Wordnik.com.  [Blogs de Ciência] Reference

Urochordata! "as well as a good bit of its content, is drawn from my love of tunicates.    From Wordnik.com.  [SEEDMAGAZINE.COM] Reference

(2003) Chimerism following fusion in a clonal ascidian (Urochordata).    From Wordnik.com.  [PLoS ONE Alerts: New Articles] Reference

"Urochordata," Gus says, walking in.    From Wordnik.com.  [Analog Science Fiction and Fact]