148 SPECIES OF THE SYSTEMA. 
PIN WN A: 
Pinna vudts. 
The colouring appears to be a more constant character im 
Pinna than it is esteemed in most genera; hence it is more 
than probable that the ferruginous six-ribbed rudis of the 
‘Museum Ulrice’ was distinct from the horn-coloured species, 
with from five to eight ribs, of the ‘Systema Nature.’ ‘Three 
very dissimilar Pinne are referred toin the synonymy, two of 
which (those delineated by Rumphius and Ginanni, the former 
not being sulcated or ribbed, the latter having nearly twenty 
sulci) are at variance with the indicated characteristics. Ar- 
genville’s engraving 1s not so unlike the ideal, but was appa- 
rently drawn from a broken spécimen ; it has been quoted by 
Dillwyn for his carnea, and by Lamarck for his jflabellum, 
which latter, purified in its synonymy, seems identical with the 
former. The young of that shell is, indeed, horn-coloured, but 
assuredly not of very coarse structure (“ rudior’’). 
The Pinna generally recognised for this shell is the one 
figured for it by Chemnitz (Conch. Cab. vol. vii. f. 773), and as 
no better identification can indisputably be suggested (more- 
over, “ List. Conch. 378, f. 214,” and “ Seba, Mus. 3, t.’92, f. 1,” 
are cited by the younger Linné), the name may be preserved 
to it, as the probable rudis of the ‘Museum Ulrice :’ that of 
the ‘Systema’ is more doubtful, and is not elucidated by the 
contents of the Linnean cabinet, where no shell there present 
corresponds accurately with the described features. There is a 
small reddish fragment of either a young rudis (of authors), or 
of an adult carnea (Chz. f. 769), which, although identical, per- 
chance, with the shell in the Royal Museum, suits not “ cornei 
coloris” of the ‘Systema.’ Our author, however, would cer- 
tainly have regarded the two shells as identical. 
The variety B (added only in the final edition) is a distinct 
species, which has been quoted, and not without reasonable 
probability, by Chemnitz, as identical with Pinna nigra (Chemn. 
