Mr. Barnes's Reclamation of Unios. 363 



All these, except the last, are known to us as well charac- 

 terized, and perfectly distinct ; and to persons less cautious than 

 we are, the northwestern expedition might have afforded an 

 opportunity of increasing the number. (See Journal, vol. vi. 

 p. 279.) 



This paper of Mons. Achille Valenciennes, on the Naiades 

 terminates, with an account of two Anodontas : the first is 

 called Anodonta glauca, which is said to be new. It is well 

 known to us, and is Mr. Say's Anodonta marginata. The 

 Anodonta has numerous varieties, but I have yet seen no evi- 

 dence of more than one species ; although Lamarck de- 

 scribes fifteen, Mr. Say, two ,• this author, two ; and others, 

 more. In the same way it would be easy to increase the 

 number to a hundred ; but they would all be more alike than 

 the numerous varieties of the Unio purpureus. The identical 

 variety here figured has been brought from our southern wa- 

 ters, and laid on the table of the Lyceum, without being sup- 

 posed worthy of particular notice. 



The next the author calls Anodonta purpurea, which with- 

 out doubt, is another of Mr. Say's genus Alasmodonta. This 

 is evident from the figure, and the following part of the de- 

 scription. " Cette espece est ties remarquable par l'epaisse- 

 ment du bord inferieur, sous les crochets." I believe that no 

 one ever saw an Anodonta thickened about the beaks. They 

 are always thin, and uniformly thin throughout. But this is 

 not all. " Ce bord un peu releve, semble montrer un com- 

 mencement du dent, et conduire ainsi vers la charniere des 

 mulettes." This again is never found in the proper Anodon~ 

 ta, but it is a very good description of a young Alasmodonta 

 before the teeth of the hinge are fully formed. When this 

 shell is again examined the learned author will find, if my 

 conjecture is right, on the inside, near the hinge, where the 

 shell is thickened, a tinge of yellow. The animal, when ex- 

 tracted, was yellow, and had a rank, offensive smell, different 

 from the fresh and not unpleasant smell of the Unios. The 

 description of the Unio Mans, mentions the same appearance 

 about the cardinal tooth, " sous cette dent le test est tres- 

 epais : il devient ensuite tres-mince." This is an exact de- 

 scription of the Alasmodonta, which is common to several 

 species, but not often seen in the Unio, and never, to my 

 knowledge, in the Anodonta. 



We are gratified to perceive, that the method of measur- 

 ing shells, and inserting the length, breadth, and diameter ; 



