150 SPECIES OF THE SYSTEMA. 
Pinna nuvicata. 
Our author neither possessed this species nor has added 
aught in his manuscript to its published description. Since 
none of the cited figures exhibit the characteristic of alter- 
nately spineless.ribs, a peculiarity insisted upon in the ‘ Mu- 
seum Ulrice,’ it is manifest that we must not regard them as 
actual representations of the shell intended, but only as sug- 
gestive approximations to it. Moreover, they appear to belong 
to several species. Lister’s figure (omitted from the synonymy 
in the ‘ Museum Ulrice,’ perchance as bearing less resemblance 
to the type than did the rest) represents the young of a West 
Indian Pinna furnished with five or six raised striz, or ribs, 
only, and consequently by no means answering the expression 
“striis plurimis.” Rumphius, in his cited illustration, has de- 
lineated a Pinna, which resembles the preceding in its sub- 
lanceolate contour, but is arrayed with more numerous and 
more closely disposed costelle. Gualtier’s broadly triangular 
species, P. vexillum? ?) is utterly unlike either. 
Of the supposed identifications of the Linnean original, 
Born’s muricata is so briefly described by him as to require 
elucidation itself. That author, however, who makes no men- 
tion of the alternation of armed and unarmed ribs (a character 
which, although essential in one or two Pinna, was possibly 
accidental in the present case), has quoted, likewise, both Knorr 
(Delic. pt. 6, pl. 20, f. 1) and Petiver; the former of which I 
regard as most agreeable to the ideal shaped from the Linnean 
description ; the latter is a mere copy from the cited figure of 
Rumphius. 
A similar synonymy has been likewise ascribed to the spe- 
cies by Chemnitz, save that he has erroneously referred to 
Seba (vol. iii. pl. 92, terminal bottom figures), whose engraving 
(cited by Lamarck for P. nobilis) neither corresponds with the 
characters specified by Linneus, nor with those delineated in 
the ‘Conchylien Cabinet.’ The drawing in the last-named work 
answers admirably to the description in the ‘Museum Ulrice,’ 
except that the scales are delineated as tubular, an error cor- 
