174 Miscellanies. 
are compressed in most specimens; and the next change we find, is 
in the Hyria avicularis, (Lam.) in which the cardinal tooth is some- 
what lamellar and forms nearly a line with the lateral tooth. The 
next ‘nuance’ is in the Symphynota levissima, (Nob.) which pos- 
sesses lamelliform cardinal and lateral teeth forming nearly a com- 
plete arc. Then follows the Symphynota bi-alata, (Nob.) the uninter- 
rupted curved tooth of which is little more than an elevated line under 
the ligament and beaks. As far as one may be able to judge from a 
bad description and very bad drawing, the Dipsas plicatus, (Leach,) 
may be with propriety se at the end of this suite.’ 
Mr. Lea’s critical examination of Lamarck’s species of the genus 
Unio constitutes a valuable part of the introduction to his paper, read 
before the Philosophical Society, March 6th, 1829; and we extract 
the substance of it for the satisfaction of those persons who may 
ever have were themselves with the determination of Uniones by 
the aid of Lamar 
ee ee aa margaritifera. Say. 
Mya margaritifera. Lin. 
There can scarcely be a doubt but 
that it is a young shell of No. 1 
Consists of the age vatietios 
of several speci 
. Embraces the ieee of Le Sueur, 
2. U. elongata, Lam. 
3. U. crassidens, Lam. 
the crassus and undulatus, of Barnes, 
rassidens of 
4. U. peruviana, Lam, 
name must take the precedence. 
Its habitat is probably the U. States, 
and not Peru. 
5. U. rariplicata, Lam. A variety of No. 4 
Answering in every respect to the 
recta, but in habitat. 
Descriptions too imperfect to ad- 
6. U. purpurata, Lam. ; 
7. U. ligamentina, Lam. fr a oe ie being Fentified a 
8. U. o bliqua, Lam 
9. U. retusa, lan. oui 
individu 
eae are a fro this country- 
10... 0. poise Lam. 
11. U. coarctata, Mere varieties of the complanatus. 
22. U. shieparedeidi Lam. ? 
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