ARCA. 91 
Chama arctirella. 
The Chama arcinella (Sowerby, Genera Shells, Chama f. 3) 
of authors is present in this collection, as declared by Linneus, 
and alone agrees with the definition of the species. The term 
“sessili” is changed to ‘“‘dentato” in the revised copy of the 
‘Systema Nature.’ 
9 
ARCA. 
Modiolus and pilosa were the sole additions made in the 
twelfth edition to the Arce published in the previous one. 
Arca tortuosa. 
The Arca tortuosa (Reeve, Conch. Icon. Arca, pl. 13, f. 86) 
of most writers still remains in the box marked for this species 
in the Linnean cabinet. The synonymy and very peculiar 
aspect facilitated its early identification. ‘‘Latus superius 
leve est” is the manuscript addition of our author in his 
revised copy of the ‘ Systema.’ 
Arca Nox. 
The Mediterranean Arca Noe (Reeve, Conch. Icon. vol. ii. 
Arca, pl. 11, f. 72) is still preserved in the box thus marked in 
the Linnean cabinet, and alone of the shells present in the 
collection agrees with the definition. 
