PALAEONTOLOGY. 4O/ 



Burmeister (1843), an d Beyrich; by the Englishmen, 

 Portlock (1843), Salter, Phillips, and MacCoy ; and the 

 Frenchman, Marie Rouault (1847). Dalman and Burmeister 

 proposed a precise nomenclature for the individual parts of 

 the body, and the special terms were still further increased by 

 Beyrich, Salter, and Barrande. For the purposes of systematic 

 arrangement, Dalman and Goldfuss used especially the presence 

 or the absence of eyes, Quenstedt the number of the body 

 segments, Burmeister l the capability of rolling up, the 

 characters of the pleura, and the general form of the body. 

 Emmrich proposed to use the external characters of the eyes as 

 a systematic feature, and pointed out the systematic importance 

 of the " facial suture" in the head shield of the Trilobites. 



The publication of Joachim Barrande's admirable monograph 

 of the Bohemian Trilobites (1852, and Supplement 1874) 

 marked a great advance in the knowledge of Trilobites. All 

 that had been previously known about these fossil Crustacea is 

 carefully considered in this work, and new observations of high 

 value are added. In so far as Barrande elucidated the con- 

 stitution of the eyes, the structure of the carapace, the 

 phylogeny of a number of genera, his results have been fully 

 accepted by later authors, but the application which he made 

 of the characters of the pleura in his systematic scheme has 

 not been adopted. 



There could be little unanimity of opinion regarding the 

 relations of the Trilobites to the living Crustacea, so long as 

 nothing certain was known about the character of the append- 

 ages in the extinct group. Zoologists were always inclined 

 to emphasise the resemblance of Trilobites with living Isopods, 

 but Burmeister pointed out the essential difference between 

 the two orders ; after a series of comparative researches he 

 concluded that the "feet" of the Trilobites had been of a 

 soft character, much as is now presented in the Phyllopods, 

 and that in many respects the Trilobites showed close affinity 

 with the Xiphosura. Gerstaecker assigned (1879) the Trilo- 

 bites to the Entomostraca (Gnathopoda) as an independent 



1 Hermann Carl Burmeister, born 1807 at Stralsund, studied Medioine 

 and Natural Science in Greisswald and Halle, began his career as a 

 gymnasium teacher and University tutor in Berlin ; in 1837 became 

 extra-Ordinary Professor of Zoology in Halle, in 1842 full Professor; in 

 1850 and 1856 travelled to Brazil, the Argentine and Chili, and in 1861 

 was called to Buenos Ayres to be Director of the Natural History Museum, 

 which he had been instrumental in establishing; died there 1892. 



