26 



SYNOPSIS OF 



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ARCUATE. 



*crassissinius. Fer. Des Moul. Gral. 

 Mya crassissima.f Klein. 

 Unio auiicularis.f Speng. 

 Uiiio margaritacea. Drap. 

 Unio sinuata. Lrzm. Blain. Pfeif- 



Desk. 

 Unio lugosa.f Poir. ? 



*monodontns. .Say. jEa^ 

 Unio soleniforniis. Lea. 



*emarginatus. Lea. 



Being unacquainted willi the following species, 

 I have deemed it, best simply to insert a list of them, 

 with the hope of their being determined at a future 

 period : — 



Unio rubens. JMenke. 



Unio rugatus. JMenke. 



Unio Grocnlandicus.f SchrO. Fer. 



Unio orientalis. Fer. 



Unio nitidens. Fer. 



Unio oblusus. Fer. 



Unio preciosus. Fer. 



Unio pulchellus. Fer. 



Unio purpuriatus. Say. 



Unio niusivus.f Speng. 



Unio gibbus.f Speng. 



Unio truncatus.f Speng. 



Unio pviformis. Con. 



Unio furvus. Con. 



Unio Juiiani. Rang. 



Unio psammoica. U'Orh. 



Unio rhuacoica. D^Orb. 



Unio Foniainiana. D'Orb. 



Uniohyloea. D'Orb. 

 Unio Guaraniana. D'Orb. 



The following species are supposed to exist in a 

 fossil state. As the casts only are usually observ- 

 ed, it must be a matter of great doubt as to the pro- 

 priety of making species where that is the case ; — 

 Unio crassiusculus. Sow. Flem. 



Unio concinnus. Soic. Flem. 



Unio uniformis. Soiv. Flem. 



Unio acutus. Sow. Flem. 



Unio Listeri. Soiv. Flem. 



Unio Solandri. Soio. Flem. 



Unio porreclus. Sow. 



Unio compressus. Sow. 



Unio antiquus. .Sow. 



Unio aduncus. Soio. 



Unio cordiformis. Soic. 



Unio crassissimus.^ Sow. Flem. 



Unio subconstrictus. Soio. Flem. 



Unio hybridus. Sow. Flem. 



Unio Urii. Flem. 



Unio abductus. Phil. 



Unio peregrinus. Phil. 



Unio pelrosus. Mart. 



Unio tumulatis. Mart. 



Unio terrenus. Mori. 



Unio saxulura. Mort. 



II. SUBGENUS MARGARITANA.§ 



TRIANGULAR. 



*com[)lanala. Lea. 



Alas, complanala. Bar. Hild. 

 Symp. complanala. Lea, Trans. 

 Am. P. S. 



t On the aulhority of Ferussac. 



J This name is pre-occiipied by Ferussac. 



§ The genus Margaritana was proposed by Shumacher in his " Essai d'un Nouveau Systeme des Habita- 

 tions des Vers Testaces," published in 1817, for the Mya margaritifera, Lin. {Unio elongata. Lam. and Mlas- 

 modonta arcuata. Bar.) Mr Say, in 1818, proposed to establisli this same division luuler the generic name of 

 Alasmodonta. The Danish zoologist having priority of date must have his name preferred, unless, as Mr Gray 

 thinks, Leach's name of DamaUs has priority of both. Unfortunately, I have not the means of referring to his 

 description. 



