THE FAMILY NAIADES. * 143 



ADDENDA. 



Unio Katherinee.f Lea. 



*Margaiitana Fianciscana.:|: Lea. 

 Monocondylssa Franciscana. Mori. 



t Testa obovatd, insequilaterali, subcompressd ; valvulis subcrassis ; natibus prominu- 

 lis ; dentibus cardinalibiis magnis, later alibus subrectisque ; margaritd alba. 



Just as this sheet was going to press I had the pleasure to receive a coramunlcation from 

 Lady Katherine Douglas, of St Mary's Isles, Scotland, accompanied by three beautiful views, 

 drawn by her ladyship, of a shell from Lake Superior, which appears to me not to have been 

 before observed. Wishing that it should be appended to this Synopsis, I have given a short 

 description of it, taking the liberty to propose that lady's name for it. At a future period I 

 hope to be able to present it with a figure from her drawings. Its place in the preceding 

 arrangement would be immediately after U. purpuratus (Lam.), being an obovate, smooth, 

 non-symphynote Unio. 



% Since this sheet was in type I have received from M. Moricand, of Geneva, a speci- 

 men of this interesting shell. Its place in this Synopsis would be between M. calceola and 

 Bonellii, under the division subrotund, smooth, non-symphynote Margaritanse. I owe to 

 the kindness of this gentlemen also the U. rotundus (Spix and Wagner), and find it distinct 

 from U, Paranensis (nobis), a matter which has been doubted by M. Moricand. 



