NOTICE. 



In presenting this series of illustrated monographs to the public, 

 the editor wishes to express his thanks to those friends who have 

 assisted him by permitting the use of their specimens, and by drawing 

 up those monographs which appear under their names. He is also 

 grateful for the general support with which he has been honoured 

 during the progress of the work. The difficulties experienced in col- 

 lecting the necessary information, the great labour and expense of the 

 illustrations, and the comparatively slow return of the capital employed, 

 are the reasons for those long intervals between the appearance of the 

 Parts, which have been so much complained of. 



As the latter difficulty gradually gives way, the former will be over- 

 come, as the editor will be enabled to give more time to the work, and 

 to obtain increased assistance in the subordinate departments. 



The editor having heard of those who woidd wish to possess the work, 

 but are deterred from doing so on account of its slow appearance, begs 

 to suggest that their subscriptions would contribute towards the re- 

 moval of the evil which they deprecate. If a small number of additional 

 subscribers were obtained; if a few of the more affluent subscribers 

 would take a second copy ; and others, by shewing the present volume 

 to their friends, were to induce them to join in patronizing the under- 

 taking, there would be no difficulty in producing the parts at short and 

 regular intervals. Those who are anxious for such a result may pro- 

 mote it in this way. 



As one effect of that increased support which has akeady commenced, 

 it will be seen that in the latter Parts a larger number of plates has 

 been given, and the letter-press has been fuller in proportion, than in 

 the earlier Parts. It is intended to carry on the work in future on 

 the same scale of increased liberabty ; and the editor cherishes a hope 

 that the successful termination of the present volume will so far add to 

 the list of subscribers as to enable him to proceed with greater rapidity 

 with the successive monographs. 



The ' Thesaurus Conchyliorum ' will in future be published at No. 70, 

 Great Russell Street, Bloomsbury, to which place Mr. G. B. Sowerby, 

 Sen., P.L.S., is removing his stock of Books, Minerals, Fossils, and 

 Shells. Among the latter will be found many of the species described 

 and figured only in the monographs, as well as others more generally 

 known. G. B. Sowerby, Jun., having made arrangements to assist in 

 the business, will be happy to supply the desiderata of those who may 

 favour him and his father with their commands. 



