The muscular tissue consists primarily of processes from the bases of the epithelial cells, processes which are contractile in nature and may be distinctly striated.
The cartilage is shaded and dotted, and the bony centres are light and striated.
They are minute structures having a round or oval shape, concentrically striated, and frequently showing a small nucleus-like body or cavity in their centre.
The muscles are arranged, jn ten or more layers, and are transversely striated.
The body is enveloped by a thick striated protective cuticle which is frequently raised into hooks or spines.