98 SPECIES OF THE SYSTEMA. 
directly inflected. The contrast, indeed, between the sub- 
central station of the beaks in Jineatus, and their oblique 
position at the extremity of the ligament in decussatus, 1s 
in fact the most striking distinctive feature. Bonanni’s 
wretched drawing, which we discover from his words, rather 
than from his graver, to be intended for the European glyct- 
meris, was only selected in default of any better representation 
being then extant. 
The assigned locality (Jamaica) is apparently namreat the 
species being a native of the Antilles. 
Arca pectunculus. 
The Linnean cabinet contains a marked example (Crouch, 
Introd. Conch. pl. 8, f. 12) of this species, which, from the 
correctness of its synonymy and the ample details in the 
‘Museum Ulrice, has always been recognised by concho- 
logists. It is the Pectunculus pectiniformis of more modern 
writers. In the revised copy of his ‘Systema,’ our author has 
substituted “t.,239, f. 73” for the more circuitous mode of 
citation required by the plates not having been numbered 
in the earlier copies of Lister’s ‘ Historie.’ 
Areca glvctierts. 
The name of this variable species was taken by our author 
from that applied to it (Chama glycimeris) in Lister’s en- 
eraving, and since the common Guernsey shell there delineated 
answers the requirements of the specific diagnosis, and accords 
likewise with the assigned locality, the species is thus clearly 
and definitely established: a marked example (Turton, Dithyra 
Brit. pl. 12, f. 3) in the Linnean cabinet confirms the conclusion. 
Of the other figures mentioned in the synonymy of the tenth 
edition, that of Rumphius, although it exhibits somewhat the 
shape of this Pectunculus, does not even belong to the same 
genus; Gualtier, pl. 72, f. G (omitted altogether, not transferred 
to another species, in the twelfth edition) presents, indeed, the 
