Leptocardia

Lep`to`car´di`a

    (lĕp`tô`kär´dĭ`å)
n. pl.1.(Zool.) The lowest class of Vertebrata, including only the Amphioxus. The heart is represented only by a simple pulsating vessel. The blood is colorless; the brain, renal organs, and limbs are wanting, and the backbone is represented only by a simple, unsegmented notochord. See Amphioxus.