oral plate การใช้

• Ventrally, the ventral lip of the mouth is armed with long series of small oral plates which recall those of heterostracans.
• An element of the median oral plates ( that would correspond to the lower lip or chin in gnathostomes ) extends out in a long rod-shaped appendage, called the " pseudorostrum . " The tail is long and slender, and has large rows of thick scales.