205 
It does not reach the attributed magnitude of M. crenatus, Lam., 
a species which was supposed by that author to inhabit the coast of 
Carolina ; but if either of the different figures of Lister, Sowerby, 
or that of the Encyclopoedia Methodique is a tolerably correct 
representation of it, I have certainly not met with it. PI. 50. 
[Notes on 4th page of cover of part v.] 
Add to the synonyms of M. papuana, Lam. Lister, pi. 1057. 
In the observations on Sigaretus perspectivus in No. 3, I remarked its 
striking similarity to Cryptostoma leachii, Blainv. On further compari- 
son I find that it cannot be generically separated from that species, and 
the reader is therefore requested to alter the name to Cryptostoma per- 
spectiva, nob. Analogy also indicates the change of Sigaretus maculatus, 
nob., Cryptostoma maculata. We shall in our next number give the 
generic character of Cryptostoma, to be substituted for that of Sigaretus, 
which latter can be retained until we publish a species of that genus. 
In the 2d edition of the Regne Animal, Cuvier, in a note to the genus 
Cryptostoma, says, that a species was sent from Carolina by Mr. L’Her- 
menier. This was doubtless one of the above, perhaps the perspectivus, 
nob., and to which he gives the name of Cr. carolinum, Cuv., not being 
aware that I had long since described it. 
Of Unio glebulus, N., Mr. Barabino has recently sent me some fine 
specimens from Bayou Teche, one of which is four inches and three- 
tenths broad, and two inches and four-fifths long. 
A Venericardia was presented to me several years since by my brother, 
who obtained it on the coast of New Jersey. I described it under the 
name of cribraria, but as the specimen is imperfect I did not publish an 
account of it. It is longitudinally ovate-orbicular, with twenty slightly 
elevated ribs, more distant from each other than their width, decussated 
by concentric, almost equally elevated lines. Length one inch and 
about three-twentieths, and breadth one inch and one-twentieth. 
Can this be a variety of the borealis of Conrad ? Having but a single 
specimen I cannot determine this question. 
[Am. Con., part vi., April, 1834.] 
Unio nexus. — Desc. Shell transversely triangular, subrhomhoi- 
dal, much inflated, thick ; beaks prominent ; anterior side much de- 
pressed, in its middle elevated so as to make an almost rectilinear 
hinge margin, with a hroad, shallow groove, which extends from the 
beak to the anterior margin; anterior margin forming nearly a right 
