84 SPECIES OF THE SYSTEMA. 
the Jamaica Plicatula in Sloane’s folio (so habitually cited by 
Linneus) is not without significance. 
There is no number 2 in the ninety-ninth plate of Gualtier : 
the interpolation of the letter E in the revised copy explains 
the error, the second figure E (the first one represents a true 
Spondylus) being a fair representation of a Plicatula. In both 
Gualtier and Rumphius, the folds are represented as simple 
(not ramose), and as tolerably numerous (“circiter plicis 
decem,” M. U.), and this pictorial definition harmonises with 
the features of the shell still preserved in its marked box in 
the Linnean cabinet. This shell, which alone in the collection 
agrees with the definition of plicatus, seems a bleached example 
of the common Chinese Plicatula, figured for imbricata in the 
‘Thesaurus Conchyliorum’ (vol. i. pl. 91, f. 15, 16). 
In an interleaved copy of the tenth edition of the ‘ Systema,’ 
our author has added the following details :—“ Rudis, crassa, 
subimbricata, seu rugosa, longitudinaliter plicata, subeequivalyis, 
magnitudine extimi articuli pollicis; intus alba; cardo exacte 
congenerum.” 
C..HA.. MA. 
Chama cor. 
Of the shells present in the Linnean collection, the well- 
known Isocardia cor (Poli, Test. Sicil. vol. ii. pl. 23, f. 1, 2), in 
which J include the I. Hibernica of the ‘ Conchologia Iconica’ 
as a variety, will alone agree with the direct and indirect defini- 
tion of this species. In confirmation of this long-established 
identification, our author has cited “ List. t. 275” in his manu- 
script, where also he has substituted “natibus revolutis” for 
“natibus recurvatis,” and suppressed the “rima hiante.” The 
published synonymy is correct, except the reference to Argen- 
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