vi INTRODUCTION. 



divisions, which would only serve to perplex and render the 

 attainment more difficult. 



As the Naiades, or shells of this country, are given in sev- 

 eral valuable scientific works lately published, we have only 

 slightlv touched them in the place they are intended to oc- 

 cupy. 



We cannot expect that the work now presented to the pub- 

 lic is free from imperfections ; but we ask for their lenity and 

 kind forbearance to excuse whatever defects there may be in 

 our humble attempts to advance the cause of science. Con- 

 chology, like other departments of natural history, is pro- 

 gressing ; and that which is given to-day is almost always 

 susceptible of being modified to-morrow ; should this work 

 be well received, it is our intention to give, as soon as prac- 

 ticable, an enlarged work, containing even the minute micro- 

 scopic shells and the fossils, with plates containing types of 

 as many species of the genera as can possibly be obtained. 



The plates were drawn and coloured with great care and 

 accuracy from the natural shells in our own cabinet, under 

 the superintendence of Mr. James Ackerman, artist. 



T. W. 



