4 HISTORY 



In 1S21, two distinguished French naturalists entered this field. Latreille, whose fame 

 as a student of the Articulata needs no illustration, strangely enough overlooked the manifest 

 characters which placed the Trilobites among Crustacea, and pronounced for their affinity 

 with Chiton. Audouin, on the contrary, compared them with the Isopod Crustacea, 

 declared they had no feet, but appendages for breathing organs, and, in short, led the 

 way, as Burmeister admits, for all subsequent research in the same direction. 



Then followed Wahlenberg's work, and Brongniart's ' Histoire Naturelle des Crustaces,' 

 a work in which the genera of Trilobites were first defined, and seventeen species 

 described. Schlotheim soon raised these to twenty-six, and Dalman's complete treatise 

 on the group in 1826 gave a new importance to the subject ; while the very perfect state 

 of the Swedish specimens enabled him to present better figures than had before appeared. 

 He called the group Paleada, and altered some of the generic names without much 

 reason, but in this he has not been followed. 



De Kay in America, and Count Sternberg in Germany, meanwhile, described many 

 forms ; and Eichwald and Razumousky, in Russia, prepared the way for Dr. Pander's careful 

 treatise, in which the labrum, first observed by our countryman Charles Stokes in American 

 specimens, was fully described. 



Dr. Green's monograph, in 1832, was only valuable for the casts which illustrated it; 

 and up to the time of the publication of the ' Silurian System,' in 1837, but very little was 

 known about Trilobites in England. That work, however, had a wide fame, and deservedly 

 so, and by costly illustrations of the best specimens procurable, and by the philosophic 

 remarks contributed by Dr. McLeay, gave a new impetus to the collection and description 

 of the species. Dr. Buckland, a year before, had illustrated some of the more common 

 kinds in his 'Bridgwater Treatise.' 



But the period was now coming for the scientific arrangement of the facts collected. 

 Illustrations were abundant both in England and on the Continent, especially in Sweden 

 and Norway, where Sars and Boeck, Esmark, Hisinger, and other authors, had done their 

 best to make the Scandinavian species known. About 1837 Prof. Burmeister began to 

 turn his attention to the group, and Dr. Quenstedt, of the Mineralogical Museum of 

 Berlin, published some important observations with regard to the number of rings in the 

 body, which Burmeister justly regards as of great consequence. It is doubtful whether 

 the honour belongs to Burmeister or Quenstedt of first calling attention to this, the chief 

 means of distinguishing the various genera, as well as a point of great importance in 

 determining the affinity. Dr. Burmeister, at all events, suggested it to Quenstedt, and 

 afterwards worked it out, considering that Trilobites differ from all other Entomostraca in 

 having no definite fundamental number of segments to the thorax, while the living Ento- 

 mostraca and Malacostraca are ruled by different but always definite numbers. 



While these investigations were going on, Dr. Emmerich succeeded Dr. Quenstedt in the 

 care of the Berlin Museum, and followed out his researches by a complete and beautiful 

 essay, well known as the * Dissertatio Inauguralis,' Berlin, 1839. In this work the author, 



