Pvn H,i I'UitlS

160 ARCIM.
lias a differently constructed hinge-apparatus, and only
one, nearly central, adductor muscle.
The first to point out the difference between Limopsis
and Pectunculus (although he retained both in the old
Linnean genus Area) was the celebrated Italian palaeon-
tologist Brocchi, who, in his 'Conchiologia
fossile Suba-
pennina/ described the species which I now propose to
record as indigenous to the British seas. His description
and remarks are (as usual) most excellent, and he
especially noticed the similarity of his Area aurita to
the Ostrea lima of Linne in respect of the triangular
cavity in the hinge. The history of the present genus
is involved in some obscurity, owing to the rarity of the
work in which it was originally published. This was
done by Sassi in the ' Giornale Ligustico di Scienze,
Lettere, ed Arti '
(fascicolo quinto) for September
1827. The British Museum library does not contain
the work ; and it is only through the kindness of
Prof. Lessona of Genoa that I have been enabled to
refer to it. Nyst, in his f
sils of Belgium '
Catalogue of the Tertiary Fos-
(1843), professed to be ignorant of
Sassi's publication or its date, although Bronn, in his
f
Lethsea Geognostica/ had given both these particulars
twelve years before this statement was made by Nyst.
The last-mentioned author, in conjunction with Gale-
otti, had in 1835 renamed this genus Trigonoccelius.
The late Pro-
Nyst altered the name to Trigonocalia.
fessor D'Orbigny, equally disregarding the rule of priority
in scientific nomenclature, gave, in the c Paleonto-
logie Francaise' (1844), another name,
that of Pectun-
culina. This has been lately adopted by Dr. Chenu in
his very useful ' Manuel de Conchyliologie et de Pale-
ontologie conchyliologique '; but he most unaccount-
ably makes Limopsis and Trigonoccelia subgenera of Pec-