The definition was not precisely similar in words to that of the
'Systema,' but the sense varied but little. It ran as follows:--
Testa oblonga, membranaceo-fragilis, basi angustata. Cardo nullus, sed
valvis altero latere coadunatis ut una appareat.
P. RUDIS. _P._ rugosa squamis fornicatis per seriem digestis.
The name of this shell, identified (I think wrongly) by our author
with the one he had termed _rudis_ in the 'Systema,' was originally
_fornicata_.
P. NOBILIS. _P._ squamis canaliculato-tubulosis subimbricatis.
P. MURICATA. _P._ striata, squamis concavis ovatis acutis.
"List. Hist. t. 370. no. 215," and "Sloan. Hist. i. p. 254," were
present among the original synonyms.
P. ROTUNDATA. _P._ squamis obsoletis, testæ margine rotundato.
P. SACCATA. _P._ nuda saccata erectiuscula.
P. DIGITIFORMIS. _P._ nuda digitiformis incurva.
P. LOBATA. _P._ nuda lobata.
* * * * *
In addition to the printed species, an anomalous _Pinna_, which I doubt
not was the _Lingula anatina_, is here described.
P. VIRIDIS. _P._ ovalis, basi compressa.
Generis dubii huc relata, donec certiora determinentur.
Testa utraque ovali-oblonga, viridis, intus magis pallida; quasi
compressa, et fere naviculata, acutior.