10 INTRODUCTION. 



Razoumowsky's observations (1826) are aphoristic, and are limited only to some forms from 

 the neighbourhood of the Ladoga Lake, all of which were already known. StscheglofFs 

 treatise (1827), on the Trilobites of Petersburg!!, written in the Russian language, I only 

 know through Pander's work. The latter careful observer treated the same subject (1830) 

 with great minuteness, but without important results. He certainly succeeded in partially 

 reducing Eichwald's species, but he himself mistook his own species, and considered them 

 as new ones, which is not the case with any one of them. The general part of his 

 work exhibits the greatest diligence and research, but it also shows an entire want of 

 knowledge of living Crustacea, owing to which it was impossible for the author to 

 communicate new and certain information on tlie structure of the Trilobites. Eich- 

 wald, Razoumowsk}', and Pander, however, also recognized the peculiar swelling at the 

 lower side of the cephalic shield, which lies before the mouth, first observed by Stokes, 

 and which corresponds with the dypeiis of the Crustacea and Insects. Goldfuss (1828) en- 

 deavoured to give information on the feet of the Trilobites, which had hitherto escaped the 

 attention of observers, but although he explained their structure correctly in a theoretical 

 point of view, his illustrations are not calculated to convey the idea they are intended to 

 represent. The endeavours to trace these organs in our fossil remains must always remain 

 unsuccessful, since it is impossible that parts of such a tender nature as we must suppose 

 them to have been, judging from the living analogues of the genus, can have left trace of 

 their existence. Tlieir very absence in fossils most distinctly proves their former real 

 structure. 



Next to Pander's work there was published (in 1832) Green's ' Monography of the 

 American Trilobites,' a work abounding in names and words, but as poor in really available 

 facts. Indeed, if the author had not also caused plaster casts of his best specimens to be 

 manufactured, it would liave been impossible to recognize even one half of the really new species 

 from his descriptions and illustrations. This period, indeed, was rich in a number of publi- 

 cations on the subject, the appearance of which was of no great importance to the furtherance 

 of our knowledge, and the value of which was very correctly estimated by L. v. Buch, 

 when he considers them as of less consequence than " two important observations of 

 Quenstedt in Wiegmann's Archives," on which I shall soon more particularly enlarge. Among 

 these writers we may enumerate Zenker, the more recent (1833) observer of Bohemian 

 Trilobites, the results of whose labours were already successfully portrayed in the same 

 year by Count Sternberg. Kloden's statements also, respecting the structure and mode of 

 living of the Trilobites on those remains which are found in the Mark Brandenburg (1834) 

 only contain ill-founded assertions. This certainly cannot be asserted of Sai''s communi- 

 cations (Isis, 1835), although not all the species are new which he describes as such. We 

 regret that the same may be said of Murchison's description of the English Trilobites, 

 given in his great and excellent work on the ' Silurian System of the British Islands' 

 (London, 1837). The author, being merely a geologist, has preferred allowing W. S. M'Leay 

 to speak on the zoological affinity of these animals, but the peculiar ideas of the latter are 

 not calculated to afford a real explanation of such questions. The division of the Crustacea, 

 in which the AnqjJiipocles (together with the Isopodes), Trilobites, and Entomostraca are enume- 

 rated as three subdivisions of equal value with one great principal group, which is considered 

 as founded in nature, is not calculated to create any great confidence in the systematic talent 



