Maiocercus

Maiocercus celticus is a species of early trigonotarbid arachnid from the Upper Carboniferous of Westhoughton, Lancashire, UK. The species was first described in 1902, with a "new species" being described in 1911 which has been proven as being a junior synonym of M. celticus.
M. celticus is the type species of the genus Maiocercus.
Originally zoologist Reginald [Innes Pocock] compared M. celticus to Brachypyge, with later evidence showing that Brachypyge had "opisthosoma which were much longer than wide; with the pleural laminæ of the second and third pleura-bearing terga being inclined slightly backwards" with Maiocercus having the "opisthosoma much wider than long; the pleural laminæ of the first, second, third, and fourth sterna being inclined slightly forwards".
The original drawing which showed Maiocercus described a pitting on the underside of the slightly forwarded laminæ, with a non-uniform concavity on the outer margins of them. The concavity is most well-marked in the fifth, sixth, seventh and eighth somites, with the opposite happening on the second, third and fourth somites.