134 



liEA S SYNOPSIS OF 





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ARCUATE. 



*crassissimus. Fer. Des Moul. Grat. 

 Mya crassissima.f Klein. 

 Unio auricularis.f Speng. 

 Unio raargaiitacea. Drop. 

 Unio sinuata. iam. Blain. Pfeif. 



Desk. 

 Unio rugosa.f Poir. ? 



*monodontus. Say. Eat. 

 Unio soleniforrais. Z.ca. 



•^emarginatus. Lea. 



Being unacquainted with the following species, 

 I have deemed it best simply to insert alist of them, 

 with the hope of their being determined at a future 

 period : — 



Unio rubens. JWenke. 



Unio rugatus. Menke. 



Unio Groenlandicus.f SchrO. Fer. 



Unio orien talis. Fer. 



Unio nitidens. Fer. 



Unio obtusus. Fer. 



Unio preciosus, Fer. 



Unio pulchellus. Fer. 



Unio purpuriatus. Say. 



Unio musivus.f Speng. 



Unio gibbus.f Speng. 



Unio truneatus.f Speng. 



Unio oviformis. Con. 



Unio furviis. Con. 



Unio Juliani. Rang. 



Unio psammoica. D^Orb. 



Unio rhuacoica. D'Orb. 



Unio Foniainiana. D^Orb. 



Uniohyloea. D'Oz-i. 

 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. Sow. Flem. 



Unio uniformis. Sow. Flem. 



Unio acutus. Sow. Flem. 



Unio Listeri. Sow. Flem. 



Unio Solandri. Sow. Flem. 



Unio porrectus. Sow. 



Unio compressus. Sow. 



Unio antiquus. Sow. 



Unio aduncus. Sow. 



Unio cordiformis. Sow. 



Unio crassissimus.:}: Soic. Flem. 



Unio subconstrictuo. Sow. Flem. 



Unio hybridus. Sow. 

 Unio Urii. Flem. 

 Unio abductus. Phil. 

 Unio peregriiius. Phil. 

 Unio pelrosus. JMort. 

 Unio tumulatis. JMort. 

 Unio terrenus. JMort. 

 Unio saxulum. JMort. 



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II. SUBGENUS MARGARITA NA.§ 



TRIANGULAR. 



*complanata. Lea. 



Alas, complanata. Bar. Hild. 

 Symp. complanata. Lea, Trans. 

 Am. P. S. 



t On the authority of Ferussac. 



X This name is pre-occupied 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 ^las- 

 modonta arcuaia, Bar.) Mr Say, in 1818, proposed to establish this same division under the generic name of 

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

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

 description. 



