INTRODUCTION. 



SECTION II. 



The object of the present work is the carrying out such an illustration of the subject 

 in all its parts. Having almost e.xclusively occupied myself with the study of the Articulata, 

 especially of insects and crustaceous animals, I have collected the materials upon which I 

 based my undertaking with diligence and circumspection ; I have most carefully tested all 

 analogies as well as more remote relations ; I have frequently consulted with my friends ; 

 and I have thus gradually pi'ogressed with my subject until the present moment, when 

 leisure is at last afforded to me to devote myself entirely to the work, and to present it to 

 the public in its present state. 



Previous, however, to communicating my own researches, I beg to lay before my 

 readers a short sketch of the information which has hitherto been known respecting the 

 Trilobites. 



SECTION III. 



The first author who wrote on these remarkable animals was Edward Lhwyd, Curator 

 of the Ashmolean Museum at Oxford. He discovered two fragments and one entirely 

 preserved specimen of the Ogyyia Buclm, near Llandeilo, in Carmarthenshire, of which he 

 sent drawings to the well-known zoologist Martin Lister, also a superintendent of the 

 Ashmolean Museum. The latter gave them to the public in the twentieth volume of the 

 ' Philosophical Transactions.' Lhwyd owns in his letter that he did not know what to make 

 of tliese fragments ; in Fig. 8 of the accompanying plate we recognize, however, with 

 tolerable certainty, a cephalic shield of the genus Trinudeus of Murchison, {CryjjtoHflnis, 

 Green,) and the Ofjijgia (Fig. 15) is perfectly evident ; but Lhwyd explains it to be the skeleton 

 of an unknown fish. The same author published in the year following his ' Ichnographia 

 Lithophyl. Britann.,' and therein enumerates thirty specimens already observed by him ; 

 but those before alluded to are again mentioned, the first under the name of Trinudeus fimbriatus 

 vuhjaris, the subsequent Dudley fossil as Bur/Iossa curta sirif/osa. These communications, 

 the earliest we possess on the Trilobites, were soon followed by others in all parts of 

 Europe, but although the number of observations was thus increased, the knowledge of 

 these animals made no progress, principally because correct comparisons with living forms 

 were wanting. They therefore appear in subsequent authors merely under newly-invented 

 names, which partially indicate very incorrect comparisons, the inappropriateness of which is, 

 however, excusable, since the observers of the Continent were only acquainted with mutilated 

 specimens, or with mere caudal shields, and therefore were much inclined to mistake these 

 remains for shells. One author (Hermann) calls them Fcctunculites trilohis imbricatus, another 

 (Scheuchzer) compares them with Patella, a third (Bromell) fancied that he recognized in 

 them the remains of insects, while a fourth (Brückmann) also compares them with shells, call- 

 ing them Armata veneris, and so also does Waltersdorf, who, in his System of Minerals, styles 

 them ConcJiitcs irihlus, connecting together the different designations of his predecessors in 

 " Käfermuscheln," and " Muschelsteine." But the correct view of the natural affinity of 

 the Trilobites was announced at almost the same period. Their anomalous form induced a 



