478 CARBONIFEROUS TRILOBITES OF AUSTRALIA, 



description as having any scientiHc value, for there is no evidence 

 to show whether his text or figure is correct, the tj^pe specimen 

 having been destroyed in the Garden Palace fire of 1882. 



The next consideration is whether the present fossil, or even 

 De Koninck's, is specifically identical with P. eichwaldi Fischer. 

 Accepting the types given by Dr. H. Woodward* as fully 

 reliable, the author does not believe it a difficult task to prove 

 the aegative. 



1. Dimensions. — The relative lengths to widths of the parts of 

 the author's fossil and that of P. eichwaldi Fischer, are, respect- 

 ively, for cephalon 14 : 28 and 17 : 27; thorax 17 : 28 and 17 : 31 ; 

 pygidium 9:13 and 1:1. 



The dimensional differences, as these measurements show, place 

 the fossils apart; but these are not nearly so important specifi- 

 cally as the following. The pygidium of F. eichwaldi is semi- 

 elliptical, and the length equal to the width: that of the author's 

 is sub-semicircular; that is, if the centre of the junction of the 

 second axial ring with the third be taken for centre, the portion 

 of the pygidium posterior to this forms a semicircle; and the 

 length is only two- thirds of the width, approximately. There are 

 up to sixteen rings in the axis, and twelve to fourteen pleural 

 divisions in the pygidium of P. eichwaldi; while, in the local 

 one, these divisions are eleven and eight, respectively. Then, in 

 the former, the pygidial border is depressed; in the latter, tlie 

 curve of convexity of the pleurae continues uninterruptedly across 

 the border to the outer edge. In the former, also, the genal 

 spines are long; in the latter, very short, only extending past 

 the first thoracic segment. These differences are sufficient to 

 prove that the author's specimen is not F. eichwaldi Fischer, and 

 the same conclusion may be drawn in respect to De Konincks 

 fossil. 



In several respects, this species resembles G'rij/ithides ylobiceps 

 Phillips; but the proportionate lengths of the thorax and pygidium 

 of the latter are different from those of the former; as also is the 

 proportionate length of the cephalon to these same parts. In 

 the former, there is no lobe connecting the eye-lobe with the 

 * Mon. British Trilobites, Pt. i., 1883. 



