INTRODUCTION. 



SECTION VI. 



Having thus traced the history of tlie Trilobites in detail, and almost completely, I 

 shall now terminate this part of my work, since, after the publication of M. Brongniart's 

 work, the multitude of authors increased with every year, insomuch that a mere enumera- 

 tion of them would be not only wearisome but superfluous, since the contribution of each 

 individual being merged in the general progress of the study, the latter only requires 

 to be made prominent. We find, however, that the exertions of naturalists henceforward 

 were especially directed to the establishment of species, and to the publication of new 

 forms, and that a variety of errors have been committed in this respect, which principally 

 originated in the defective knowledge of the structure of the body of the Trilobites, and in 

 the imperfect fragments upon which such new species have been founded. An immense 

 number of new names and characters has therefore certainly accumulated, but by no means 

 in the same ratio is the number of really new facts. Even monographists of some districts 

 in which remains of Trilobites are found, have not been able to guard against confound- 

 ing species already known with supposed new ones. If I were now to enter upon the 

 particular proofs of such errors, it would lead me into an investigation of the differences of 

 species, and thereby cause subsequent repetitions ; I limit myself therefore to a short 

 notice of those works which have excited attention, and on that account deserve a par- 

 ticular notice. 



Dalman's ' Treatise,' published in I82G, is, next to Brongniart's ' Monography,' the most 

 important work on Trilobites, but it does not add any important new facts in a general 

 point of view, and by no means determines the zoological affinity of the Trilobites de- 

 cisively. In the particular point of the establishment of species, it is only richer and more 

 complete than Brongniart's work with reference to Sweden. The author's proposal to use 

 the appellation of Palaadcs, instead of the family name of Trilobites, has met with no appro- 

 bation, nor does it merit such, since nothing more is expressed by it than by the older name, 

 which at least indicates correctly a portion of the family characteristics. 



The Trilobites, however, were made the subject of researches at many different places, 

 almost simultaneously with Dalman, and many new forms and views were thereby more 

 intimately explained. Dekay (1824) was the first who described the North American 

 Trilobites in several treatises, but his results were not appreciated by the scientific men of 

 Europe till afterwards. Count Sternberg (in 1825) described the Trilobites of Bohemia with 

 his usual accuracy, and had in Boeck (1827) a successor equally careful and ingenious. It 

 is to the latter that we are particularly indebted for a correct view of the facial line or suture, 

 which extends through the cephalic shield. Payton wrote on the Trilobites at about the same 

 period in England, but I am not able to say with what success, since I have never seen his work. 

 Four authors were within a short time successively employed on this subject in Russia, who 

 furnished by their joint efforts many valuable contributions. Eichwald, the earliest of them 

 (1825), gave a perfect monography of the Trilobites of Esthonia, and also enlarged on their 

 zoological affinities. His endeavour, however, to trace the analogy of the Trilobites with the 

 Isopodes was not more successful than his establishment of thirteen different species was accu- 

 rate. After carefully analysing them, we can only recognize in them four really distinct species. 



