THE FAMILY NAIADES. 



31 



E-i 

 Z 

 O 

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 K 

 p« 

 S 

 t- 



Oi 



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o 

 z 



s^ 



OVAL. 



*gigantea.f Lea. 



subvexa. Con. 



*Slewartiana. Lea. 



*gibbosa. Say. 



An. iiifiala. Major Le Conte's Cabi- 

 net. 



*granclis. Say. Lesueur. 

 An. coipulenta. Coop. 



SUBROTUND. 



*suboibiculata. Say. 



OBOVATE. 



*obtusa. Spix. 



An. lituiatiim. Spix. 



*siiionos. D'Orb. 



*Patagonica. Lam. 



a 



o 



s 



OBOVATE. 



*Iato-marginala4 Lea. D'Orh. 

 An. trapezius ?§ Spix. 

 An. lotundus'? Spix. 



*Spixii. D'Orb. 



porcifer.|| Gray. 



*trapezialis. Lam. Blain. 



An. exotica.^ Lam. D'Orh. 

 An. giganteus. Spix. 

 An. pencillatus? Gray. 

 An. Siisannaj. Gray. 

 An. ladiatLis. iSpix. 



""anserina. 



Spix. 



Georgina;. Gray. 



Paiisliii.ff Gray. 

 Leila Parishii. Gray. 



*Blainvilliana.|| Lea. 

 An. trapezialis. Crouch. 

 Iiid. trapezialis. D'Orh. 



t ^n. giganteus, Spix., having been before described by Lamarck under the name of trapezialis and ex 

 otica, my species must retain this name. 



J The Fatagonica and lato-marginata, when they are better observed, may prove to be the same. 



§ Spix's figure so closely resembles the lato-marginata, that 1 scarcely feel a doubt as to their being the 

 same. He does not, however, notice the broad margin which is so characteristic of this species. 



II Never having seen this species, I place it here on Mr Gray's authority. 



1[ So far as I have been enabled to examine specimens of this and trapezialis, I am disposed to think they 

 are not distinct species. 



tf On the authority of Mr Gray. 



ft In my description of Blainvilliana (Vol. I. page 189), I observed that I was induced to believe that the 

 animal of this shell would be found to differ from that of.the genus Anodonta. M. D'Orbigny, in his Synopsis of 

 the Fresh Water Shells of South America, has in fact so found it. The animal has two tubes. Nevertheless, 

 although I then proposed if such should be the case that it should be placed in a new genus, under the name of 

 Columba, I have continued it in the subgenus Jlnodonta, as, with the present artificial system, which is founded 

 on the hinge, it could not with propriety be elsewhere classed. When the family shall be arranged in a system 

 founded on the animal structure only, it evidently must be changed, and I doubt then if it should be placed in the 

 Iridina, for although it is likely that all the species of that genus have two tubes, they do not seem to possess 

 the deflected palleal cicatrix, which I noted in the descriptioH of Blainvilliana. 



