The former Suborder of PTYCHOPARIIDA was 2002 seperated as self-sufficient order cause of morphological discrepances (lack of rostral plate, conspicuous brim along the complete cephalons volume, limited sutures). The HARPETIDA are a small and relatively homogeneous Order. Most conspicuous feature of this Order is the big horseshoeshaped cephalon with its typically very broad preglabellar field.

The HARPETIDA are including the Families Harpetidae, Harpitidae and Entomaspididae.

The image shows a representative of the Family Harpetidae.

Scotoharpes sp.

Middle Cambrian to Upper Devonian.

Cephalon

As a rule the big cephalon's running out into broad genal spines at posterior thorax regions level, respectively posterior of the pygidium. The sutures are running ophistoparian or they are articulately shrinked. The convex glabella, featuring 1 to 3 pairs of furrows, is anterior tapering. As a rule the eyes are reduced to bulging tubercles  .

Thorax

The thorax consits of at least 12, but mostly of more up to 30 segments. The rachis is protuding articulated. The flat pleura featuring furrows articulated.

Pygidium

The short tail shield is smaller (singnificant) than the Cephalon. It reduces itself posterior.