The very natural genus _Pecten_ was separated from the unsymmetrical
oysters, with the following definition:--
PECTEN. Testa subrotunda, altera planior, basis transversa, anguli
transversi (auriculæ) ad basin. Cardo cavitas conica, striis utrinque 3
longitudinalibus obliquis.
The genus OSTREUM, enlarged by the addition of the true oysters
confounded with the _Mytili_, the _Meleagrinæ_, _Aviculæ_, and the
_Anomia placenta_, was thus characterized:--
O. MAXIMA. _Pec._ radiis 14 rotundatis longitudinaliter striatis.
In place of Gualtieri, "List. Ang. 184. t. 5. f. 29. Pecten maximus,"
and "Faun. Suec. 1343" were referred to: these synonyms had been added
subsequently to the description.
O. JACOBÆA. _Pec._ radiis 14 angulatis, fornicis longitudinaliter
striatis.
The cited drawing of Gualtieri was not mentioned.
O. ZICZAC. _Pec._ radiis 18 explanatis.
No specific name was attached to this, the preceding, and the next two
species.
O. STRIATULA. _Pec._ radiis 16 obliteratis, transverse
membranaceostriatis, margine integerrimo.
O. MINUTA. _Pec._ radiis 20 convexis.
O. PLEURONECTES. _Pec._ radiis 12 duplicatis, extus lævis.
O. OBLITERATA. _Pec._ radiis 24 duplicatis, extus lævis.
O. RADULA. _Pec._ radiis 6 convexis decussate striatis, margine crenato,
auriculis æqualibus.
O. PLICA. _Pec._ radiis 16 convexis læviusculis, decussato-striatus.
No specific name was appended to either this, the next, or the two
preceding species.
O. PALLIUM. _Pec._ radiis 12 convexis, striatus, scaber, squamis
imbricatus.
This with the remainder of the _Pectens_ (as far as _flavicans_) formed
a group characterized by "Auricula altera intus ciliato-spinosa."
O. NODOSA. _Pec._ radiis 9 nodoso-vesicularibus.
O. PES-FELIS. _Pec._ radiis 9, lævis, fornice squamis fornicatis.
The printed diagnosis, or heading, was evidently drawn up from a
different shell.
O. PELLUCENS. _Pec._ radiis 9, lævis, fornice squamis
cochleari-hemisphæricis.
No name was attached to this or the next shell.
O. SANGUINEA. _Pec._ radiis 22 scabris, semiauritus.
The reference was not to plate 74 (as printed) of Gualtieri, but to
plate 73. "Purpureus nigro undatus" was written after the indicated
colouring.
O. VARIA. _Pec._ radiis 30 scabris explanatis.
"Et omnia cadem" followed "sanguineæ"; "striis compressis echinatis" was
not present; "color pallidior" was in the place of "concolor."
O. PUSIO. _Pec._ radiis 40 filiformibus.
O. GLABRA. _Pec._ radiis 10 lævibus planiusculis, internis striis
elevatis duplicatis.
Gualtieri's rude drawing was not quoted.
O. OPERCULARIS. _Pec._ radiis 20 subrotundis, decussate striato-scaber,
operculo convexiore.
O. GIBBA. _Pec._ radiis 20 glabris, gibbus.
Brown's drawing was not quoted.
O. FLAVICANS. _Pec._ radiis 8 striatis, margine altero rotundato.
As in the 'Systema,' the next two shells, along with this, formed a
group distinguished as having the "Valvulis altero latere magis gibbis."
No names had been appended to this, the three preceding, and the two
following species.
O. FASCIATA. _Pec._ radiis 20, auriculis æqualibus exoletis.
The "gibba" of the borrowed diagnosis was not, it may be observed, in
the original.
O. LIMA. _Pec._ radiis 22, imbricatis squamis, altero margine rotundato,
auriculis obliteratis.
The "gibba" of the borrowed heading was not in the original diagnosis.
The final remark was likewise absent.
O. ISOGNOMON. The entire account of this species was added to the copy
in the Linnean handwriting. "Klein, 128. t. 8. f. 15. Isognomon" and
"Cardo ut ephippo" had been omitted in printing.
O. MALLEUS. _O._ trilobum.
"Transverso ad marginem" was a subsequent addition.
O. FOLIUM. _O._ ovatum, lateribus obtuse plicatum.
Klein's copy (t. 8. f. 22.) of the indicated figure in Rumphius was
cited, in the handwriting of Linnæus: the "cavitate conica" was an
emendation.
O. EDULE. _O._ subrotundum semiorbiculatum, valvula altera plana
integerrima.
There was no semicolon after "opaca," but a comma after "latiore." The
original sole synonym was the omitted one of "Gualt t. 102. f. B."
O. SEMIAURITUM. _O._ semiauritum ovatum læve, basi obliqua.
Linnæus himself had added this species to the earlier catalogue.
O. EPHIPPIUM. _O._ submembranaceum curvum, cardine octosulcato.
In addition to the published _Ostreæ_, the following description of the
shell subsequently termed _O. perna_ (Syst. ed. 12.) was found in the
manuscript:--
_O._ rugosum, inæquale, tumidiusculum, cardine octocrenato.
Testa perniformis, obovata, substantia ligni antiqui, tumidiuscula,
superficie obsolete rugosa, inæquali interne livida. Cardo transversus,
margine inflexo, notatus crenis obtusis circiter 8.