Arionellus

Arionellus Barrande, 1850, is a disused name for a genus of trilobite. The name Arionellus was a replacement for Arionides Barrande, 1847, itself a replacement for Arion Barrande, 1846 , which was preoccupied because Férussac had already used it in 1819 for a genus of slugs.

Agraulos had already been proposed as replacement for Arion by Hawle and Corda in 1847, but Barrande unjustly considered it a homonym of Agraulis, a butterfly named by Boisduval in 1836.

The species of Arionellus have now been reassigned to the following genera.
 * A. bipunctatus = Croixana bipunctata
 * A. ceticephalus = Agraulos ceticephalus
 * A. convexus = Camaraspis convexa
 * A. cylindricus = Keithiella cylindrica
 * A. oweni = Modocia oweni
 * A. primaevus = Strenuaeva primaeva
 * A. pustulatus = Glaphurus pustulatus
 * A. texanus = Tricrepicephalus texanus
 * A. tripunctatus = Tricrepicephalus tripunctatus