PllEFACE. V 



panion to it, should be regarded as an integral portion and 

 Appendix. It was in following up this design that our first 

 plate was numbered 9, the sequence to the eighth and final 

 supplementary plate of that useful iconography : in every 

 other respect this volume is independent of it. 



The terms "posterior" and "anterior" have been used 

 in accordance with the ideas of the older conchologists, and 

 conversely to their modern signification. This is to be 

 regretted, and has only been continued to the end, in order 

 that the phraseology should harmonise throughout. 



Allusion has already been made to the long period which 

 has elapsed since the commencement of these pages. It 

 behoves us now to furnish the several dates of their publica- 

 tion. Sheets b, c, were separately issued at the close of 

 1842,* and conjointly (p. 1 to 144) with the seven suc- 

 ceeding ones in the early part of 1843, almost simul- 

 taneously with plates 9 to 13, and their explanatory text. 

 Sheets l to s (p. 145 to 272) appeared at the close of the 

 same year, and were followed, about a twelvemonth after, by 

 plates 14, 15, 16 ; and at a long interval (two years or there- 

 abouts) by plates 17, 18, 19. Sheet t (p. 273 to 288), 

 although it has been printed for many j^ears, now makes its 



* Under the title of ' Lamarck's Species of Shells.' The letter- 

 press was accompanied by two plates, the figures in which had been 

 transferred to stone from our first five plates (on which they had 

 been somewhat promiscuously engraved, having been designed for 

 lithographic transposition) and the earlier engravings of the ' Index 

 Testaceologicus.' The publisher, dissatisfied with their execution, 

 discontinued the work, w r hich should contain 3 plates and 224 

 pages. 



