456 NEW GENUS AND SOME NEW SPECIES 



Remarks. — This is a beautiful shell. It is remarkable in 

 being connate behind the ligament; this connection, how- 

 ever, is very small, and only perceptible in perfect specimens ; 

 in the old ones it is separated. Fine specimens have been in 

 our cabinets for years without our observing they were con- 

 nate. The cardinal tooth being double in the right valve 

 seems to have escaped the attention of the observant Mr Say. 



9. Symphynota Cygnea. 



Testa ovatd, antice lata et rotundatd. irregulariter transversim ru- 

 gosd ; natibus retusis ; valvulis tenuibus et post ligamentum connatis. 



Shell ovate, wide before and round, with irregular transverse wrin- 

 kles ; beaks not prominent ; valves thin and connate behind the liga- 

 ment. 



Hab. rivers and lakes of Europe. 



My Cabinet. 

 Mytilus cygneus. Lin. Gmel. p. 3555. 

 Anoilonta cygnea. Lam. 



Remarks. — It is a matter of surprize to me that this shell, 

 so long known and so often described by European concho- 

 logists, should not have been before observed to be connate. It 

 has not to my knowledge been thus described. Among about 

 a dozen specimens received from various parts of Europe, I 

 have two which are decidedly and undoubtedly connate. One 

 w r as sent to me by Count de Yoldi of Copenhagen, the other 

 by W. Swainson, Esq. of London. These are the only spe- 

 cimens I have seen with the dorsal margin unfractured, and 

 it may be that even in their native beds they rarely exist in 

 a perfect state with regard to this part. Young specimens 

 would be more likely to be found perfect, if taken from pools 

 or lakes where they remain undisturbed by the attrition of 

 sand, &c. carried over them by the action of the water. 



