Editing Trilobite (section)

====Hypostome====
{{Further|Hypostome (trilobite)}}
[[File:Trilobite hypostome types based on attachment (labeled).png|right|upright=2.25|thumb|Illustration of the three types of hypostome. Doublure is shown in light gray, the inside surface of the cephalon in dark gray, and the hypostome in light blue. The glabella is outlined in red broken lines.]]
[[File:Asaphus expansus ventral.jpg|thumb|''Asaphus expansus'' ventral side prepared, showing the attachment of the hypostome|left|209x209px]] The hypostome is the hard mouthpart of the trilobite found on the ventral side of the cephalon typically below the glabella. The hypostome can be classified into three types based on whether they are permanently attached to the rostrum or not and whether they are aligned to the anterior dorsal tip of the glabella.

* '''Natant''' – Hypostome not attached to doublure. Aligned with front edge of glabella.
* '''Conterminant''' – Hypostome attached to rostral plate of doublure. Aligned with front edge of glabella.
* '''Impendent''' – Hypostome attached to rostral plate but not aligned to glabella.