BY JOHN MITCHELL. 479 



glabella, though, indeed, tlie eye or palpebral lobe is very close 

 to, and only faintly separated from, the basal lobe of the glabella. 

 The eye, too, is relatively larger, the pygidial border is wider, 

 and the glabellar frontal lobe less globular ; the free cheek- 

 border and glabellar limb narrower, and the eyes less prominent 

 and more posteriorly situated in the former than in the latter. 

 Tiie British species, too, was much larger than the New South 

 Wales one. 



The specific name was chosen for it because of the strong con- 

 vexity of its pygidium. 



Log. and I/or. —Glen WilUam, about two miles from Clarence- 

 town, Parish Parr, County Durham. Lower Carboniferous. 



Griffithides sweeti Eth. fil. 



Grijfithides siveeti Eth. fil., Proc. Linn. Soc. N. S. Wales, (2), 

 Vol. ix., Pt.3, pp.5-28-9, PI. xxxix., fig.3, 1894. 

 (PI. liii, figs.1,2). 



Through the courtesy of Mr. G. Sweet, of Melbourne, the 

 type-specimen of the species is before me, and I regret that, 

 owing to the incompleteness of its cephalon, it fails to elucidate 

 certain difficulties met with in considering the thoraces and 

 pygidia from the Mt. Morgan area, assumed to belong to 

 PhiUipaia woodtrardi Eth. fil., or to settle whether G. siveeti Eth. 

 fil., and that species are not identical. All the numerous pygidia 

 obtained from the Mt. Morgan area, except those which belong 

 to P. siaitvellensis, P. rockltatnptonensis, and P. inoi-yaiietLsis. 

 have thirteen axial, and eleven pleural divisions; and, aftermost 

 careful and repeated inspection, 1 have to conclude that Mr. 

 Etheridges G. sweeti has the same number of divisions in the 

 axis and pleurie of its pygidium; also the same kind of pygidial 

 border and furrow: and, in fact, its pygidium cannot be sepa- 

 rated from pygidia which are the most plentiful in the Mt. 

 Morgan distiict, and which I have tentatively considered to 

 belong to P. woodwardi, or at least to those cephalons represented 

 on PI. li., figs. 12 and 13, l)ecause these, too, were the most 

 plentiful cephalons occurring in the same area. As regards the 

 head-shield of G. sweeti., sufficient of it has not been conserved 



