Light micrograph of a Planaria, which is a turbellaria, or free-living flatworm. Shows pharynx in transverse section, lobes of the intestine and the layers of muscles. Flatworms are primitive, bilaterally symmetrical animals which show the beginnings of a head and true organs. however, the mouth is still the only opening into the gastric system and there are no circulatory systems apart from the gut; there is a primitive brain and nervous system. Magnification x30 at 6x7cm.