ADDENDA. 



Since the preceding sheets have gone through the press I 

 have described or seen the following new species : — 



Page 



Unio Dorfuillianus, Lea, should follow U. asper - - - 15 



graniferus, Lea, should follow U. verrucosus - - 16 



Rangianus, Lea, should follow U. Ravenelianus - 22 



Menkianus, Lea, should follow U. interruptus - 24 



discus, Lea, should follow U. Burroughianus - - 29 



Cailliaudii, Fer., should follow U. platyrhynchus 35 



contradens, Lea, should follow U. Tappanianus - 39 



An. Nuttalliana, Lea, should follow An. Benedictensis 4S 



Wahlamatensis, Lea, should be first in the subgenus 48 



Oregonensis, Lea, should follow An. cygnea - - 50 



pavonia, Lea, should follow An. edentula - - - 50 



chiziana, Rang., should follow An. uniopsis - - 50 



Newtonensis, Lea, should follow An. incerta - - 51 



exilis, Lea, should follow An. Buchanensis - - - 54 



Tetraplodon pectinatum, Spix., is Unio ambiguus. (nobis.) 

 (Castalia atnhigua. Lam.) 



Diplodon ellipticum, i^pz'.r. Unio multistriatus ? Lea. 



To the synonyms of ,/2n. fluviatilis, page 51. add ^^n. mar- 

 ginata, Say. 



