Diplorrhina

Diplorrhina Hawle and Corda (1847) is a genus of trilobite belonging to Order Agnostida. It lived during the early Middle Cambrian (Amgan and Mayan stages) in what are now the Czech Republic and the North Siberian plateau. as in members of the family Peronopsidae it lacks a preglabellar furrow. Both cephalon and pygidium lack spines. It is difficult to distinguish "Diplorrhina" from many other peronopsids.
Taxonomy.
The ancestor of "Diplorrhina" is most likely one of the Siberian species of the genus "Archaeagnostus". "D. recta" is the most primitive species and it gave rise to "D. cuneifera", which was in turn ancestral to "Diplorrhina triplicata".
Description.
Both border and border furrow of the cephalon are relatively narrow. The transglabellar furrow is straight or curved slightly towards posterior. The posterior glabellar lobe is parallel sided, has two pairs of lateral furrows and small basal lobes; there is no median node. The pygidial border is flattened and wide with posterolateral angles, but no spines. The pygidal lobes reach the median node but do not cross the axis. The distance between the pygidial axis and border furrow is short or sometimes touching.
Differences with "Peronopis".
"Diplorrhina" differs from members of the subgenus "Peronopsis (Peronopsis)" in the better developed transaxial furrows, better developed lateral furrows of the glabella, larger basal lobes, and in the trend towards the formation of a transverse depression of the axis.