FAMILY NAIADES.-!^™*. 



GENUS MARGAEON, 



I. SUBGENUS TRIQUETRAL 



All the species preceded by an * are in my Cabinet. The inner column forms the Synonyms. 



TRIANGULAR. 



*corrugata. Lea. 2 



Syria corrugata. Lam. Sow. 

 Syria rugosa. Cuv. 

 Syria rosea. Lefev. Pot. 

 Mya angulata. Wood. 

 Unio corrugata. Slain. 

 Unio rugosus. Wagner. 

 Paxyodon ponderosus. Schum. 

 Triplodon rugosum. Spix. 



*subviridis. Klein. 



Myasyrmatophora. Gronovius. Ghnel. 

 Wood. Dill. Schreib. Schrot. 



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TRIANGULAR. 



Syria avicidaris. Lam. Ohild. 



Crouch. Desk. Gruerin. 

 Syria syrmatophora. Soiv. Cuv. 



Desk. Schom. 

 Syria elongataP Swain. 

 Syria cordata. Menhe. 

 Unio caudatus. Wagner. 

 Prisodon obliquus. Schum. 

 Diplodon furcatum. Spix. 



^Browniana. Lea. 

 Syria humilis f Trosch. 4 



1 The shell known to zoologists generally as Syria corrugata, Lam., was long before placed by Klein under 

 the generic name of Triquetra {Tentamen Meihodi, 1753, p. 135, PL 9, Fig. 36), and Ferussac adopted it, very pro- 

 perly, in preference to Syria. In my former editions, I placed Syria in the subgenus Unio, but the animal has 

 been found to possess two syphons, which certainly separates it from Unio {Gray, Annals of Nat. Sist., Dec. 

 1840). Troschel, in Wiegmann's Archives, describes the soft parts and the cicatrices. The cicatrices in the S. 

 corrugata, he says, differ. He also says that the Unio delphinus belongs to this genus, as well as a new shell, 

 Syria humilis, from Guiana, described by him. 



2 It will be observed, throughout this Synopsis, that where any change has been made of generic or specific 

 names, I have placed my name there. This is not done with a view to claim any merit, but in accordance with 

 the usual custom in such cases. The object is to show the author of the change, and nothing further. 



3 Mr. Gray thinks this to be a " perfectly distinct species." I have never seen the shell, and feel too much in 

 doubt to insert it as such. 



4 Referred to in Wiegmann's Archives, 1847. 



