ANODONTA. 



47 



VII. SUBGENUS ANODONTA. 



f TRIANGULAR. 



*Wahlamatensis. Lea. 



OVAL. 



*magnifica. 1 Lea. 



Symp. magnifiea. Lea, Trans. Am. 



P. S. 

 An. rotundaius. Swain. 

 An. aurata. Kilst. 



*Woodiana. Lea. 



Symp. Woodiana. Lea, Trans. Am. 

 P. S. 



*Benedictensis. Lea. Adams. PeJeay. 

 Stimpson. 

 Symp. Benedictensis. Lea, Trans. 



Am. P. S. 

 An. cultratus. Gould. 



*Nuttalliana. Lea. 



*Californiensis. Lea. 



OBOVATE. 



*crispata. 2 Lam. 

 An. glauca. Gould. 



*tortilis. Lea. 



OVAL. 



*cygnea. 3 Brap. Lam. Crouch. Blain. 

 Pfeif. Turt. Des Moul. Flem. 

 Crrat. Bouil. Brard. Bosc. Chil- 

 dren. Pwton. Potier. Crassies. 

 Por. Klees. Morelet. Merm. 

 Forb. and Hani. Villa. Guerin. 

 Graells. Thompson. Cuv. Gray. 

 Kilst. Brown. Bouch. Mossm. 

 Desh. Studer. Menke. Gras. 

 Goupil. Pup. 

 Myt. cygneus. Lin. Chem. Sehro. 

 Pill. Muhl. Monta. Mat." Shep. 

 Tur. Miill. Schreib. Pennant. 

 Bon. Pa Costa. 



1 Mr. Gray, in Griffith's Cuvier, PL 24, Fig. 2, gives a figure, without description, of a shell, under the name 

 of Unto tenuis, which he thinks is my An. magnifiea; but it appears to me to be my Dipsas discoidea. It is 

 figured with the linear tooth of Dipsas. 



3 With some hesitation, I have placed these two species under the division plicate, as the folds or crimples are 

 so small as almost to require a lens. But to place them in the division of "smooth" shells would be, I think, more 

 objectionable. 



3 I have, after a good deal of consideration and examination of my specimens, and the figures in the numerous 

 works describing the Naiades, satisfied myself that An. cygnea and An. anatina are not specifically distinct. If 

 the observation of M. Poiret, that the first is viviparous and the last oviparous, be correct, then they should be cer- 

 tainly separated. I feel perfectly persuaded, however, that he must be in error. Turton, in his recent work on the 

 Land and Fresh Water Shells of Great Britain, says he is " inclined to think that all our supposed species of this 

 genus may be justly resolved into one." M. Gras {Description des Moll. Fluv. et Ter. de la France) says that 

 anatinus is only the young of cygneus; and Mr. Gray, of London, says, in his Manual of Fresh Water and Land 

 Shells, that it is a most variable species, and that "we must not only dissent to the division of this polymorphous 

 bivalve into these numerous species, into which it has been separated by the continental writers, but even demur to 

 the possibility of arranging the diversities of shape and coloring into strictly different varieties" — p. 156. "Like 

 Unio, this species is chiefly American, only one distinctly-marked species inhabiting Europe." Such has been my 

 opinion for more than 20 years. (See note on Unio pictorum.') 



4 (3 of Maton and Kacket (Lin. Soc. Trans., vol. iv.) is evidently, judging from the figure, Unio litoralis. 



