CONCHOLOGIOAL WRITINQS. Tl 



Aldsmodon complanatum, for instance. I shall describe here, (Mj 

 those which / have now before my eyes, and with the names given 

 them ten ySars ago, at their discovery ; I have seen a few others, 

 which I delay to describe, not having them now in my hands. Those 

 who shall purchase these new shells, may have the pleasure to. give 

 splendid figures of them, if they like. 



Since 1820, several American Conchologists have attempted to 

 notice, describe, or figure these shells ; Barnes, in 1823, Lea, Say, 

 and Eaton, later still. They had a fine field before them, in elucida- 

 ting them by good figures, and describing the new kinds ; but led 

 astray, by various motives, they have neglected to verify, or properly 

 notice my previous labors, although they were known to them. Mr. 

 Say is, above all, inexcusable. I had respectfully noticed, in 1820, 

 his previous labors ; but he has never mentioned mine, and knows 

 so little of the animals of .these shells, as to have mistaken their 

 mouth for their tail, and their anterior for the posterior part of the 

 shells I > 



If he had seen these animals alive, feeding, moving, and watched 

 their habits as I have done repeatedly, he would not have fallen into 

 such a blunder. The mouth is always near the cardinal tooth, and 

 the lamellar tooth is to the right of it in the right valve, to the left 

 in the left valve. — Others pretend that my monograph is too intri- 

 cate ; it is the subject which is such ; whenever many species belong 

 to a tribe, many divisions and sections are needed to plucidate and 

 _ [2] 

 isolate the species. All the great naturalists know and do this. 



The works wherein their erroneous labors are found cost above 

 $100 I (mine only 50 cents.) This has put it out of my power, as 

 yet, to verify all their mistaken and synonymous names. A complete 

 synonymy of these shells will soon be required, which I may perhaps 

 undertake in future, unless it is done by Mr. Poulson, who has trans- 

 lated and means to publish my monograph of 1820. Thiscontinua- 

 tion will be a supplement to his translation. I mean to give in it 

 my shells under my own names, imposed as soon as found in 1821 

 and 1822 chiefly, the undoubted right of a previous discoverer and 

 explorer. If some of them are already well named and described, 

 let their names be compared and the oldest or best prevail, as those 

 of my old Monograph ought in all cases. 0. S. R. Philadelphia, 

 Oct. 1831. 



