Prof. H. H. Swinnerton — Classification of Trilobites. 487 



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Eep. Brit. Assoc, 1908, pp. 245-67. 



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Geology in the Field, pp. 739-69. 

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II. — Suggestions for a Revised Classification of Trilobites. 



By H. H. Swinnerton, D.Sc, F.G.S., F.Z.S., Professor of Geology, 

 University College, Nottingham. 



Introduction. 



IN 1897 C. E. Beecher 1 published his "Outline of a Natural 

 Classification of the Trilobites", which has since "proved 

 superior to any previously proposed ". Nearly a score of years have 

 passed since that time and many new Trilobites have been discovered, 

 the majority of which fit into this system without difficulty and prove 

 that to a large extent it is conceived on a sound basis. A few, 

 however, do not fit in and have therefore revealed in it weaknesses, 

 the existence of which tend to hinder the systematic study of 

 Trilobites. In the following pages it is proposed to point out these 

 weaknesses and to make suggestions for modifying and extending 

 Beecher's system upon what it is hoped will prove to be natural lines. 

 On the whole the families given by Raymond in the 1913 edition 

 of Zittel's Textbook of Paleontology as edited by Eastman will be used 

 as the basis for this discussion. 



Recent Classifications. 



Beecher's classification has been adopted without modification of its 

 broad lines by English and American, but not by all Continental 

 writers. Among the latter Gurich 2 and Jaekel 3 have recently 

 suggested systems which differ materially from Beecher's. 



1 Amer. Journ. Sci., vol. iii, 1897. 



2 Centralblatt Mm. Geol. Palaeont., 1907, p. 129. 



s Zeitsch. Deutscb. geol. Ges., Bd. lxi, p. 380, 1909. 



