460 CARBONIFKKOUS TRILOBITES OF AUSTRALIA, 



Pygidiuin sub-semicircular or sub semielliptic, length 7 ram., 

 greatest width 12mm., convex, distinct indications of granulation 

 present; axis prominent, strongly convex, diminishing rapidly 

 posteriorly, ending prominently near the margin of the border 

 with about one-fourth of its anterior spread, its rings are twelve; 

 axial grooves distinct; side-lobes convex, consisting of eight 

 pairs of segments, the last two pairs being rather indistinct, first 

 pair faceted; border of moderate width, gently tumid, continuous 

 to the anterior pair of segments; undersurface striated. 



Obs. — This fossil was included by Mr. Etheridge with his 

 species Phillipsia diihia {op cit.}, but not separately described. 

 For so placing it, there appears to me to be insufficient reason. 

 That the trilobite here described is not identical with Mr. 

 Etheridge's P. duhia {P. stanvelleiisis mihi) may be made plain 

 by an explanation of their differences. 



(1 ). The free cheeks and eyes are different, as are their glabella?; 

 for though the glabella of the present species is not perfect, 

 there is sufficient of it preserved to show that, anteriorly, it 

 neither contracts nor droops as does that of P. duhia [P. 

 staiivellensis). 



(2). The neck-furrows of the two also differ. 



(3). The axis of the former is wider than one side-lobe; in the 

 latter, the axis is narrower than one side-lobe. 



(4). The axis of the former is much less prominent than that 

 of the latter. 



(5). Tn the former, the length of the thorax is much greater 

 than its cephalic or pygidial length; in the latter, both the 

 cephalon and pygidium are longer than the thorax. 



(6). In the latter, the anterior pleural segments of the pygidium 

 show distinct bifurcation; this is not visible in the former. 



(7). The genal angles of the former are strongly spinate; those 

 of the latter are not yet proven to be so. 



(8). The middle lobe of the one is wide and moderately convex; 

 that of the other, narrow and very convex. 



(9). The angulation of the free cheeks of the former posteriorly, 

 and their steep slope into the furrow are very marked, but this 

 is not so ill the latter. 



