Abstract
The genus Acanthoteuthis was founded by E. Wagner1 and G. Münster upon small booklets, sometimes isolated, sometimes associated with more or less complete remains of the animal, which are found in the Lithographic Stone of Bavaria. Münster characterized three species chiefly upon the form of these hooklets, viz, A. speciosa, A. Férussacii, and A. Lichtensteinii, and noticed the existence of a fourth. Subsequently Munster referred to this genus also a number of forms based principally upon the shape of the body and upon the form of the internal shell, but most of these were afterwards separated by A. Wagner as a new genus (Plesioleuthis). The genus Acanthoteuthis is therefore restricted to such forms as Münster described chiefly upon the form of the books.