UNIO.— Plate LXIX. 



Uiiio Mudioiifonms, Say (teste Lcii). 



Unio scaleida, Rof. ("teste Lea). 

 Hab. Western waters in N. America. 



Tlie uraboual ridge, which is ratlier wide and conspicu- 

 ous, is preceded by a broad shallow concavity. There is 

 a certain peculiarity in the extreme divergence of the 

 beaks from each other. The hinge-margin is very deep 

 in front. 



Species 355. (Mus. ILuilcy.) 



Unio .ambiguus. Un. tedd subovali, vix inceqidlaterali, 

 mibtenui, haud ve?dncosd, oUmced, vix feel miidmej 

 radlatd, ant'ici conceidrice et coiifertim subriigosd, pos- 

 tire Ireci ; mtirgiiie dorsali utriiii/UK angulalo, posiicH 

 subiicdm; maryiiie ventrali coiwexo., natibus hand 



■libus, iiiargurUd si/uallde albidd, denlibiis C(tr- 

 diiMlibua tramversis. 

 The doubtful Unio. Shell suboval, scarcely inequi- 

 lateral, rather thin, not ventricose, olivaceous, not 

 rayed (or at most very indistinctly so), densely and 

 concentrically wrinkled in front, smooth behind, dor- 

 sal edge angulatcd at each end, somewhat rising be- 

 hind, ventral margin convex, beaks not prominent, 

 nacre dirty white, cardinal teeth transverse. 

 Parkeys, MSS. in Philippi, Ah. N. Conch, vol. ii. 

 Hub. Australia. 



Runs very closely into the characters of Un'm Aiidralli, 

 Lam. (Moreiotdcus). It has neither a lunule nor an um- 

 bonal ridge. The pearl is often stained with olive-colour 

 in the umbonal cavity, and the cardinal teeth are so trans- 

 verse as to appear lateral. 



