266 [ FEBRUARY, 
very distinct species, the prastnws being much longer comparatively, with 
fewer and less prominent tubercles, and arranged in a very different manner. 
The cardinal plate under the beaks is not dilated; in the nodulatus, it is pro- 
foundly dilated, a very important difference, which it is strange should have 
been overlooked. Young shells of prasinus and bullatus, when compared, are 
strikingly dissimilar. 
(Z.) U. purpuratus, Lam. There is no doubt that Solander named this species 
ventricosa, as Humphreys terms it “ La Ventrue rouge,’’ and gives the habitat 
of ‘‘ Mississippi river,’’ where it abounds, and where no other species has beer 
found which agrees with the description. 
(m.) U. quadrulus is not U.rugosus, Barnes. Mr. Lea remarks that some of 
our best Western conchologists think U. rugosus identical with U. fragosus. 
Barnes’ figure certainly has little resemblance to the latter, and the “ broad 
nodulous, somewhat double ridge,’? wholly inapplicable to guadrulus. Mr. Lea 
says, ‘‘two specimens referred to by Mr. B. as:rwgosws, were under my inspec- 
tion, and proved to be, the one a flat metanever, and the other a plicatus.’? Now 
the rugosws may be the metaneurus, Raf., but Barnes’ figure was never intended 
for any variety of the U. plicatus. 
Mr. Say has unfortunately copied Barnes’ description of U. rugosus, and 
applied it to U. quadrulus, Raf. 
(z.) U. undatus. It has been supposed that this was the shell described by 
Mr. Lea as trigonus, but it is distinct. There isa fine specimen of wndatus in 
the collection of the Academy, which agrees perfectly with Barnes’ figure, and 
is much more ventricose anteriorly and over the umbo, thantrigonus ; has more 
elevated beaks, and is very inequilateral, whilst the latter is nearly equila- 
teral. The wndatus is equally,distinct from cordatus, Raf., which is compara- 
tively compressed. 
Compare Barnes’ description, “ subtriangular, very tumid, waved,” with La- 
marck’s description of U. obliqua, *‘ ovato-rotundate, oblique,’’ and the discre- 
pancy must strike every one; yet both Lea and Deshayes make them one 
species, 
U. undulatus, Barnes. The old specimens of this species have so much 
resemblance to Say’s heros, as even to have deceived Say himself, who aban- 
doned his species, and referred it to Barnes’s wndulatus ; but itis a very 
distinct species, the young shell having little resemblance to that of the latter. 
There can be no doubt that Barnes figured the species now known as the 
costatus of Raf. 
(o.) U. viridis, Raf. Mr. Lea gives another name to this shell, because he 
says it is not Rafinesque’s species, which it certainly is; yet he does not 
acknowledge Rafinesque as authority, for he applies his specific names, as in 
the case of U. interruptus, to a species of his own; consequently the shell in 
question should have been quoted by him as U. viridis, Con., unless he has one 
rule applicable to himself and another referable to other authors. The shell 
labelled viridis by Rafinesque himself in Mr. Poulson’s cabinet, is the same as 
Lea’s Tappianus. 
ANODONTA- 
(a.) A. cataracta, Say. The Mytilus fuwiatilis of Gmel. and Dillwyn, and 
the M. cllitus of Solander, appear to be merely names given to the Unio ochra- 
ceus in Lister’s work, t. 157, fig. 12. The two Anodontas figured by Lister, t. 
154, 155, and having Vzrg. inscribed upon the plates, 1 cannot refer to any of 
our species. 
(b.) A. marginata, Say, Dekay regarded this shell as the young of emplicata, 
and it is not unlikely his opinion was correct. It certainly is not Say’s 
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