20 



the trouble to instruct and correct aie. I am so well aware of the rea! 

 imperfections attending the labours of even the best informed that I 

 never will be displeased at the exposure of my own imperfections, 

 indeed it will always give me pleasure when convinced of them 

 to acknowledge my errors. In my published works I am aware that some 

 errors have obtained publicity — some of them caused by misapprehen- 

 sion, some also I fear by inadvertence, and I am determined, as oppor- 

 tunity occurs to point them out and give the necessary corrections. I 

 may consider it rather a fortunate circumstance for me, that most of these 

 errors are of such a nature that there exist very few persons who are able 

 to detect them. The present paper may be considered as the first fruits 

 of such determination. 



I would therefore engage the attention of malacological students to the 

 subject of the Ibllowing references . — 



DisciNA, Lamarck Hist. Nat. des Anim . sans vert, tome vi. Ire 

 partie, p. 236. 



Crania, ibid. p. 237. 



Orbicula, ibid. p. 242. 



Remarks on the Genera Crania and Orbicula of Lamarck, Trans, of 

 Linn. Soc. vol. XIIL p. 465, by G. B. Sowerby. 



Crania, i Sowerby's Genera of Recent and Fossil Shells, Nos. 



Orbicula, f 12 and 13. 



'I Fleming's History of British Animals, p.p. 376, 377. 



CRIOPUS,f * ^ '11' 



Discina, Turton's Conchylia Insul, Brit. p. 237. 



And I have referred to these five works, because there is in every one 

 of them some error in connection with this subject. 



I commence with Lamarck for two reasons, — because he is the first 

 in order of publication and because it appears that almost all the errors 

 in the other works have been caused by too implicity relying on his 

 correctness. The genus Crania was adopted by DeBlainvilleand Brugiiiere 

 from Retzius and may be considered as a perfectly well established genus; 

 Lamarck appears to have adopted it in reliance upon those authors with- 

 out being in the slightest manner acquainted with it himself; afterwards 



