136 



LEA S SYNOPSIS OF 



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2 

 <; 

 o 



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O 



03 



Oh 



O 



OBOVATE. 



*Parchappii. Lea. 

 Monoc. Parchappii. 



D'Orb. 



*Conientesensis. Lea. 

 Monoc. Corrientesensis. 



D'Orb. 



*Guarayana. Lea. 

 Monoc. Guarayana. 



D'Orb. 



*fossiculifera. Lea. 



Monoc. fossiculifera. D'Orb. 



Minuana. Lea. 



Monoc. Minuana. D'Orb. 



ARCUATE. 



*raargaritifera. Lea. 



Mya margaritifera. Lin. Chem. 



Knorr. Dill. Desk. Wood. 



Mat. Monta. Miihl. Retz. Jfil. 

 Margaritana fluviatilis. Schum. 

 Unio elongata. Lam. Mich. Bouil. 

 Unio sinuata. Pfeij. 

 Unio Roissyi. Mich. 

 Unio margaiitiferus. Pfeif. Drap. 



Tun. 

 Unio rivalis. Zeig. 

 Alas, margaritiferum. 

 Alas, arcuata. Bar. 



*Holstonia. Lea. 

 *fabula. Lea. 



Flem. 



The following species are unknown to me : — 

 Alasmodoala Tripolitana. Fer. 

 Alasmodonta incurva. Fer. 



O 

 15 



a 



n 



III. SUBGENUS DIPSAS. 



TRIANGULAR. 



*plicatus.f Leach. 



Baibata plicata.:}; Humph. 



Myt. plicatus. Soland. 



Myt. dubius. Gmel. Dill. 



Ciistaria tuberculata. Schum. 



An. dipsas. Blain. Fer. 



An. tuberculalus. Fer. 



An. alatus. Sow. 



Sympli. bi-alata. Lea, Trans. Am. 



P. S. 

 Unio bi-alata. Desh. 



rovAL. 



*discoideus.§ Lea. 



Symp. discoidea. Lea, Trans. Am. 



P. S. 

 Unio tenuis. Gray.\\ 

 An. tenuis. Gray.\\ 



the sixth one I place here with some hesitation, as to its proper situation, never having seen it. It is certainly 

 a most interesting group, and it is to be regretted that we have no description of the^animal. 



t Perfect specimens show the whole linear tooth, and the folds on the posterior slope and on the posterior 

 wing, but old and imperfect specimens sometimes exhibit neither. The imperfect figure and description by 

 Leach of this fine shell, led me to believe that it could not be the same with that which I described under the 

 name of Sym. bi-alata, 



X On the authority of Gray. 



§ The posterior termination of the tooth shows some disposition to duplication, and evidently inclines to pass 

 into the subgenus Unio. 



n In Griffith's Cuvier. 



