2 PREFACE. 



hand, I have had but few opportunities of examining original specimens from England 

 and America. My present work therefore certainly ought not to be considered as complete ; 

 it will unquestionably admit of much improvement, and for this purpose I should gratefully 

 receive any assistance, especially of original specimens of species hitherto unknown to me, 

 even if it were only for temporary inspection. Indeed I should be satisfied with good 

 figures of such specimens, provided they were accompanied by explanatory descriptions. 

 Such illustrations being rare, I have made it my principal object to render the plates contained 

 in this work as perfect as possible. I have had the good fortune to meet with an artist 

 in the person of Mr. A. Andorif, of Berlin, whose talents and whose execution of the 

 engravings are such, that I can, without the slightest hesitation, recommend the plates, which 

 were executed by him, as patterns for imitation to all artists. Every person acquainted 

 with the subject will undoubtedly agree with me, that better and more beautiful representa- 

 tions of Trilobites, or figures more true to nature in every respect, are not in existence. 



Halle; May ^th, 1843. 



