Cephalon

The trilobite body is divided into three major sections, a cephalon with eyes, mouthparts and sensory organs such as antennae, a thorax of multiple similar segments (that in some species allowed enrollment), and a pygidium, or tail section.

© Sam Gon III

The cephalon is the foremost portion of the segmented body of a trilobite. Generally this region of the body can be thought of as the "head" of the animal, including the eyes on the dorsal surface of the body, and the hyperstome (part of simple mouth) on the venter (underside), directly below the anterior edge of the glabella. It is composed to chitin, and usually fossilizes well.

Most cephalons are shaped like the front most portion of horseshoe crabs, though there is extremely wide variation in trilobite morphology.