2 



II. has presented to the Section MSS. for a ninth and final num- 

 ber, completing his work. This ninth number contains the con- 

 clusion of the descriptions of the species of Paludina, title-page, 

 preface and index, and will be illustrated by a beautiful colored 

 plate of Paludina magnifica, and a portrait of the author, with 

 autograph. 



^^ It is very important to those possessing Prof. Haldeman's 

 work, to obtain the ninth number, in order to complete it. 



Mr. Tryon's Continuation of the Monograph will contain an 

 •extensive addition to the species, their number having more than 

 doubled since the conclusion of Haldeman's work, and not more 

 than about ten per cent, of these additional species having 

 appeared in the recent publication of the Smithsonian Institu- 

 tion, — in which, moreover, they are very inadequately illustrated. 



During the past year, the Conchological Section of the 

 Academy of Natural Sciences has published, by subscription, a 

 Monograph of the Terrestrial Mollusca of the United States. 

 The edition was limited to one hundred copies, which have been 

 mostly sold, and it now proposes to issue the Monograph of 

 P^resh-water Mollusca in the same sumptuous style, and at the 

 same cheap rate ; intending eventually to complete the series by 

 works on the Melanidse, Corbiculidre, Unionidas, and Marine 

 Mollusca. 



*% Positively only 50 copies of Prof. Haldemans work, and 

 100 copies of Mr. Try on s Continuation, will be issued; and 

 immediately on completion of the work, if any copies remain un- 

 sold, the price will be advanced 10 per cent, per annum. 



None of the illustrations nor any part of the text will be pub- 

 lished in the " American Journal of Conchology." 



Prof. Haldeman's work will be issued in numbers, at intervals 

 of about three months, commencing as soon as subscriptions 

 authorize it. 



