80 rafinesque's 



105 Sp. Alasmodon viridis (L. viridis disc. 1820.) Shell thin 

 swelled, subelliptical, quadrulated, posterior slope slanting truncate 

 without ribs : outside greenish, nearly smooth, inside bluish, with 

 flexuose wrinkles. Length 1-2, diameter 1-3, axis 1-3 of the 

 breadth. 



Yar. I. Chloris. Bright green. 



Yar. II. Radiata. Olivaceous with green rays. 



Yar. III. Fuscata. Brownish. 



In the Ohio and other streams. So much like Unio viridis out- 

 side as to be easily mistaken for it. Tooth small bilobe crenate, 

 angular projection sharp with a wrinkle or furrow. One or two 

 inches broad. 



5 N. Gr. Amblamodon. 



106 Sp. Alasmodon hians {Amhlasmodon Mans, 1823.) Shell 

 thick; much swelled, elliptical, subobliqual and gaping, margin flex- 

 uolate, posterior slope with broad ribs. Outside rugose and yellow- 

 ish brown, inside even pale incarnate. Length 7-20, diameter 2-5, 

 axis 1-4 of length. 



River Tennessee, fine rare shell, 5 inches broad. Hinge quite 

 peculiar, cardinal tooth not lobed, large subcrenate, large oblique 

 knob on the projection decurreut, twisted and curved behind. 

 6. N. G. Decurambis. 



107 Sp. Alasm. scriptum {Decuramh'is literata disc. 1822.) 

 Shell rather thin, subelliptical, very much swelled, truncate behind, 

 nearly flat with transverse furrows and ribs, subsinuate beneath. 

 Outside smooth greenish with blackish spots like capital letters! — 

 inside bluish. Nearly equilateral, apex ardate. Length and 

 diameter one half, axis 5-12 of the length. 



In Green river. Wonderful shell, exceedingly rare and strange, 

 outside form of a Truncilla, 2 or 3 inches broad. Tooth flexuose 

 trilobe compressed, decurrence befid before. Certainly a peculiar 

 genus. 



108 Sp. Alasm. atropjurp)ureum {Decurambis ditto, disc. 1823) 

 Shell rather thin, elliptical, hardly swelled, smooth and not truncate 

 behind, subsinuate beneath : outside rugose, blackish purple, quite 

 inequilateral, apex hardly cordate. Length one half, diameter and 

 axis one third of the breadth. 



In the river Cumberland, very rare, 3 inches broad. Tooth flexuose 

 subtrilobe, hardly prominent. Yery distinct from the last, although 

 a true Decurambis. 



