416 NEW GENUS AND SOME NEW SPECIES 



2. U. complanatusf, Soland. MSS.< 



var. 



fers to each of the above authorities, but thinks Lister's figure is too doubtful to be 

 retained, as Solander had referred to it for a variety of Mytilus modiolus, in which, 

 however, he errs, for Lister's figure is a good representation of a small specimen 

 of the radiatus of our waters. Lamarck, in his description of U U. radiata" re- 

 fers to Lister and Gmelin, and also to the figure of Mr Say's ochracevs. The last 

 is a distinct species. Several of these writers refer also to the figure in the Ency. 

 Meth. t. 248, f. 5, which is evidently copied from Chemnitz. Mr Barnes, in his 

 description, refers to Say's U. ochraceus, Dillwyn's Mya radiata, and Lamarck's 

 U. radiata. Considerable difficulty presents itself in establishing the name of 

 this species, so well known among us by that of U. radiatus, in consequence of 

 the old writers using the same name for those from Virginia and Malabar, which, 

 I believe, when examined together, will be found specifically to differ. Should 

 this prove to be the fact, we must give to our shell the name which Lamarck has 

 described it under a second time, viz. " U. virginiana," giving it a masculine ter- 

 mination. 



* It should be mentioned here that I was not aware that Mr Barnes had pro- 

 nounced the first six to be varieties of Say's purpureus until after I had selected 

 the seven. 



t The celebrated Lister published his great work on conchology in 1685, and 

 at that early period he was in possession of several species of our fluviatile shells 

 procured from Virginia. The first he thus describes, " musculus brevior, admo- 

 dum crassus, ex interna parte subroseus, cardine incisuris minutis exasperato," t. 

 150, f. 5. Dillwyn describes this shell under the name of Mya complanata, and 

 refers to this figure. Beside the locality above, Solander gives Maryland and 

 New Jersey, and Humphreys Mississippi. The latter is most likely an error. Dr 

 Green supposed this shell, so well known to all our conchologists under Mr Say's 

 name purpureus, to be the Mytilus jiuviatilis described by Dillwyn from Gmelin, 

 and referred to Lister, t. 157, f. 12. I differ, however, in this opinion, 1. Be- 

 cause it is not described as being toothed. 2. Gmelin says, "habitat in Europas 

 aquis dulcibus." 3. The complanata answering, in description, better to our 

 shell, and being the first figured and described. It appears somewhat singular to 

 me, that the observant and able zoologist, Mr Say, had not been struck with the 

 similitude of our shell to Lister's figure and description. There is no species 

 more common in all our fresh waters, east of the Alleghany mountains, than 

 this, and nothing could be more likely than that it should be among the first to 

 be taken to Europe by the early voyagers to North America. In accordance, 



