A. ANTIQUATA. _A._ testa oblique cordata, transversim sulcata, antice angulo compresso, rima intra rhombum transversim striata. The admixture of two species (at the least) in the published edition resulted from the amalgamation of two earlier descriptions. To the above diagnosis belonged the printed details with the following important changes. In place of "extus striata longitudinaliter sulcis crenatis," the reading was simply "intus striata longitudinaliter," and in lieu of "interjecto spatio rhombeo plano," merely "rima patens." The proposed name for this shell, from a supposition of its identity with the _Pecten virgineus_ of Rumphius, was _A. virginea_. The other species which Linnæus referred to the same numerals of the 'Systema' was not named, but was thus characterized:-- A. (Sys. n. 144). _A._ cordata, sulcis nodosis, rima decussatim striata. List. Hist. ... Pecten polyleptoginglymus, &c. Gualt. t. 87. f. C. Testa reliquis magis gibba, albido-flavescens, sulcis xxx obtusis, transversim nodosis: nodis transversis, obtusissimis, imbricatis. Intus albida. Margo dentibus xxx argutiusculis. Rima sulco rhombeo circumscripta, disco decussatim vix manifeste striato. Umbones distantes ad neutrum latus flexi. A. SENILIS. _A._ oblique cordata, octosulcata, lævis, antice hians, rima obtusangule striata. Lister (without numerals!) was referred to in illustration; the early unimproved account of the beaks and ligamental area ran as follows: "Umbones distantes, oblique incurvati. Rima hians striata transversim ad angulos acutos": "et profunde immersis" was an addition. A. GRANOSA. _A._ subcordata, sulcis muricatis, rima obtusangule striata, utrinque angulum formante. The name was evidently borrowed from Rumphius, whose _Pecten granosus_ ("143. t. 44. f. K.") was referred to in the manuscript, though neither quoted in the printed copy nor in the 'Systema' (ed. x.). "Bonan. 2. n. 73," and Lister (without numerals) were also cited. A. DECUSSATA. _A._ lenticularis, decussatim substriata, apicibus reflexis. For a detailed account of this shell, to which no specific name was attached in the MS., the 'Museum Ulricæ' was referred to, previous to its publication. A. PALLENS. _A._ lenticulari-subobliqua, decussatim striata, rima brevi. This was the type referred to in the 'Systema.' A. PECTUNCULUS. _A._ lenticularis sulcata, decussatim rugosa. "Arg. t. 27. f. B," and Lister without numerals appended, were the unpublished synonyms. The expressions "leviter," "exteriore tenui; sulcata," "in arcum," were not parts of the original copy, which contained, however, the unprinted paragraph "latere interiore margine prominente notato." There was no specific name attached to either this or the next species. A. GLYCIMERIS. _A._ lentiformis, transversim substriata, rima lævi. The '_Chama glycimeris Bellonii_' of Lister (t. 247) was an unprinted synonym. * * * * *